Laylatul-Qadr is the most blessed night. A person who misses it has indeed missed a great amount of good. If a believing person is zealous to obey his Lord and increase the good deeds in his record, he should strive to encounter this night and to pass it in worship and obedience. If this is facilitated for him, all of his previous sins will be forgiven.
Praying Qiyam
It is recommended to make a long Qiyam prayer during the nights on which Laylatul-Qadr could fall. This is indicated in many hadeeths, such as the following:
Abu Tharr (may Allah be pleased with him) relates: “We fasted with Allah’s Messenger (may Allah’s peace and blessings be upon him) in Ramadan. He did not lead us (in qiyam) at all until there were seven (nights of Ramadan) left. Then he stood with us (that night – in prayer) until one third of the night had passed. He did not pray with us on the sixth. On the fifth night, he prayed with us until half of the night had passed. So we said, ‘Allah’s Messenger! Wouldn’t you pray with us the whole night?’ He replied: ‘Whoever stands in prayer with the imam until he (the imam) concludes the prayer, it is recorded for him that he prayed the whole night.’…” [Recorded by Ibn Abi Shaybah, Abu Dawud, at-Tirmithi (who authenticated it), an-Nasa’i, Ibn Majah, and their isnad is authentic]
[Point of benefit: Abu Dawud mentioned: “I heard Ahmad being asked, ‘Do you like for a man to pray with the people or by himself during Ramadan?’ He replied, ‘Pray with the people’ I also heard him say, ‘I would prefer for one to pray (qiyam) with the imam and to pray witr with him as well, for the Prophet (may Allah’s peace and blessings be upon him) said: "When a man prays with the imam until he concludes, it is recorded that he prayed the rest of that night." [Masaa’il]
Abu Hurayrah (may Allah be pleased with him) narrated that the Messenger (may Allah’s peace and blessings be upon him) said:
“Whoever stands (in qiyam) in Laylatul-Qadr [and it is facilitated for him] out of faith and expectation (of Allah’s reward), will have all of his previous sins forgiven.”
[Al-Bukhari and Muslim; the addition “and it is facilitated for him” is recorded by Ahmad from the report of ‘Ubaadah Bin as-Samit; it means that he is permitted to be among the sincere worshippers during that blessed night.]
Making Supplications
It is also recommended to make extensive supplication on this night. ‘Aaishah (may Allah be pleased with her) reported that she asked Allah’s Messenger may Allah’s peace and blessings be upon him), “O Messenger of Allah! If I knew which night is Laylatul-Qadr, what should I say during it?” And he instructed her to say:
“Allahumma innaka `afuwwun tuhibbul `afwa fa`fu `annee – O Allah! You are forgiving, and you love forgiveness. So forgive me.”
[Recorded by Ahmad, Ibn Majah, and at-Tirmizi. Verified to be authentic by Al-Albaani]
Abandoning Worldly Pleasures for the Sake of Worship
It is further recommended to spend more time in worship during the nights on which Laylatul-Qadr is likely to be. This calls for abandoning many worldly pleasures in order to secure the time and thoughts solely for worshipping Allah. ‘Aaishah (may Allah be pleased with her) reported:
“When the (last) ten started, the Prophet (may Allah’s peace and blessings be upon him) would tighten his izaar (i.e. he stayed away from his wives in order to have more time for worship), spend the whole night awake (in prayer), and wake up his family.”
[Al-Bukhari and Muslim]
And she said:
“Allah’s Messenger (may Allah’s peace and blessings be upon him) used to exert more (in worship) on the last ten than on other nights.”
Source: Shaykh Muhammad Nasir-ud-Deen al-Albaani - Adapted from “The Night Prayers: Qiyam and Taraweeh from works by Muhammad Nasir ud-Deen al-Albaani (and other scholars)”
From the Fatwas of Ibn Baaz:
Q: On this great occasion of the Night of Al-Qadr (Decree), we hope from Your Eminence to lecture to Muslims concerning it.
A: The Night of Al-Qadr is the best of all nights. Allah sent down the Qur’an in it and told that it is better than one thousand months. It is blessed and in it every matter of ordainments is decreed. Allah said in the beginning of Surah-Al-Dukhkhan, Ha-Mim. [These letters are one of the miracles of the Qur’an, and none but Allah (Alone) knows their meanings]. By the manifest Book (i.e. this Qur’an that makes things clear). We sent it (this Qur’an) down on a blessed night [(i.e. the night of Al-Qadr, Surah No. 97) in the month of Ramadan — the 9th month of the Islamic calendar]. Verily, We are ever warning [mankind that Our Torment will reach those who disbelieve in Our Oneness of Lordship and in Our Oneness of worship]. Therein (that night) is decreed every matter of ordainments. As a Command (or this Qur’an or the Decree of every matter) from Us. Verily, We are ever sending (the Messengers), (As) a Mercy from your Lord. Verily, He is the All-Hearer, the All-Knower. And He (Exalted be He) said, Verily, We have sent it (this Qur’an) down in the night of Al-Qadr (Decree) Verily, We have sent it (this Qur’an) down in the night of Al-Qadr (Decree) The night of Al-Qadr (Decree) is better than a thousand months (i.e. worshipping Allah in that night is better than worshipping Him a thousand months, i.e. 83 years and 4 months). Therein descend the angels and the Ruh [Jibril (Gabriel)] by Allah’s Permission with all Decrees there is Peace (and Goodness from Allah to His believing slaves) until the appearance of dawn. It is authentically reported that Allah’s Messenger said, Whoever observes night prayer during Ramadan, out of Iman (faith) and hoping for Allah’s Reward,
(Part No. 15; Page No. 426)
their previous sins will be forgiven. (Agreed upon by Imams Al-Bukhari and Muslim) During it, one can offer prayers, say Dhikr (Remembrance of Allah) and supplications, recite the Qur’an and do other aspects of goodness.
The noble Surah-Al-Qadr refers to that good doing in it is better than the good deeds of thousand months other than it. This is a great bounty and mercy from to His Slaves. Therefore, Muslims should glorify it and present different acts of worship during it. The Prophet (peace be upon him) told that it occurs in the last ten nights of Ramadan, especially in the odd ones. He (peace and blessings be upon him), Look for it in the last ten (nights) of the month of Ramadan in the odd (nights). Moreover, the authentic Hadeeths of the Prophet showed that this night can be any of the ten nights and is not restricted to certain night; it may be the night of twenty first or any of the odd nights. It may be the night of
(Part No. 15; Page No. 427)
twenty seventh which is the most night likely to be the Night of Al-Qadr. However, it may come in the even nights. Therefore, it is better to observe prayer, Dhikr and supplication along the whole ten out of faith and hoping for Allah’s Reward in order to secure to catch up with this night and require what Allah promised those who do so in this night. The Prophet (peace be upon him) used to show more diligence in these days than in the first twenty nights. ‘Aaishah (may Allah be pleased with her) said, The Prophet (peace be upon him) used to exert himself in devotion during the last ten nights of Ramadan more than any other time. She said: Upon the advent of the (last) ten (nights of Ramadan), Allah’s Messenger (peace be upon him) used to keep awake at night (for prayer and devotion), awake his family and prepare himself to observe prayer (with more vigor). He (peace be upon him) used to practice I’tikaaf (seclusion for worship in a mosque)mostly during them. Allah (may He be Exalted and Glorified) said, Indeed, in the Messenger of Allah (Muhammad peace be upon him) you have a good example to follow.
Also, ‘Aaishah (may Allah be pleased with her) asked the Prophet (peace be upon him) saying, O Messenger of Allah, what should I say in the Night of Al-Qadr? The Messenger said, “Say, ‘Allahumma Innaka `Fuww Tuhibbul-`Afw Fa`fu `Anny’ (O Allah, You are Most Forgiving, and You love forgiveness; so forgive me.) The companions of Allah’s Messenger and the Salaf (the righteous successors) glorified these ten days and observe during them different kinds of goodness.
Therefore, Muslims should follow the example of the Prophet (peace be upon him), his honorable companions (may Allah be pleased with them) and the Salaf of this
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nation. They should offer prayer, recite the Qur’an and Dhikr and observe different kinds of worship out of faith and hoping for Allah’s Reward so that they require the forgiveness of Allah, the removal of sins and saving from Hell as a bounty and generosity from him. The Book of Allah and the Sunnah of the Prophet indicate that this great promise is attainable as well through avoiding major sins. Allah (Exalted be He) said, If you avoid the great sins which you are forbidden to do, We shall expiate from you your (small) sins, and admit you to a Noble Entrance (i.e. Paradise). Allah’s Messenger (peace be upon him) said, The Five (Obligatory Daily) Prayers, and from (one) Friday Prayer to (the next) Friday Prayer, and from Ramadan to Ramadan, are expiations for whatever (sins committed) between them, provided that major sins are avoided. (Related by Imam Muslim in his Saheeh)
It is worthy of mentioning here that some Muslims may do their best in Ramadan and repent to Allah from the preceding sins and after the end of Ramadan return to the misdeeds which they used to have and this is a great danger.
The true Muslim should keep away from that and have a truthful intention to keep on the obedience of Allah and avoiding the sins. Allah (glory be to Him) said to His Prophet (peace be upon him), And worship your Lord until there comes to you the certainty (i.e. death). And He (Exalted be He) said, O you who believe! Fear Allah (by doing all that He has ordered and by abstaining from all that He has forbidden) as He should be feared. [Obey Him, be thankful to Him, and remember Him always], and die not except in a state of Islam [as Muslims (with complete submission to Allah)].
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Verily, those who say: “Our Lord is Allah (Alone),” and then they stand firm, on them the angels will descend (at the time of their death) (saying): “Fear not, nor grieve! But receive the glad tidings of Paradise which you have been promised! We have been your friends in the life of this world and are (so) in the Hereafter. Therein you shall have (all) that your inner-selves desire, and therein you shall have (all) for which you ask. An entertainment from (Allah), the Oft-Forgiving, Most Merciful. This Ayah (Qur’anic Verse) refers to that those who admitted that their Lord is Allah, believed in Him, devoted their worship to Him and keep on that, Angels will say to them upon death that shall be no fear on them nor shall they grieve and that their destiny is Paradise. This is the outcome of having faith in Him, keeping on obedience of Allah and avoiding sins and devoting worship to Him. There are many Ayahs that assure on this meaning and establish on the necessity of adherence to justice, keeping on it and abstaining from sins. An examples of this are the following Ayahs, And march forth in the way (which leads to) forgiveness from your Lord, and for Paradise as wide as the heavens and the earth, prepared for Al-Muttaqun (the pious). And spend in the Cause of Allah (i.e. Jihad of all kinds) and do not throw yourselves into destruction (by not spending your wealth in the Cause of Allah), and do good. Truly, Allah loves Al-Muhsinun (the good-doers). And those who, when they have committed Fahishah (great sin as illegal sexual intercourse) or wronged themselves with evil, remember Allah and ask forgiveness for their sins; – and none can forgive sins but Allah – and do not persist in what (wrong) they have done, while they know. For such, the reward is Forgiveness from their Lord, and Gardens with rivers flowing underneath (Paradise), wherein they shall abide forever. How excellent is this reward for the doers (who do righteous deeds according to Allah’s Orders).
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We pray to Allah to guide us and all Muslims in these nights and other nights to what pleases him and loves. We ask Him to protect all of us from the evils with ourselves and our misdeeds. He is the Most Generous.
Source: Taken From: Fatwas of Ibn Baaz Content > Volume 15 > Book on Fasting > The Night of Al-Qadr > The Night of Al-Qadr is the best night

(by Joel Zimmer )