Night of al-Qadr
Its virtue: The night of qadr is the most virtuous night of the year. Allaah says in the Quran (what means): “We revealed it on the night of power [that is, qadr]."
"What will tell you what the night of power is? It is better than a thousand months” [97:1-3] Any action, for example, reciting the Quran, making remembrance of Allaah, and so on, on the night of qadr is better than the same act performed for one thousand months.
When is it preferred to seek this night?
It is preferred to seek this night during the last ten nights of Ramadhaan, as the Prophet, sllallaahu 'alayhi wa sallam, strove his best in seeking it during that time. We have already mentioned that the Prophet would stay up during the last ten nights, would wake his wives, and then would remain apart from them to worship.
Which night is it:?
Scholars hold different opinions as to the exact night that is the night of qadr. Some hold the opinion that it is the 21st, some say the 23rd, others say the 25th and still others say it is the 29th. Some say that it varies from year to year but it is always among the last ten nights of Ramadhaan. Most scholars, though, vouch for the 27th.
Ahmad recorded, with a saheeh (authentic) chain, from Ibn ‘Umar, may Allaah be pleased with him, that the Prophet, sallallaahu 'alayhi wa sallam, said: “He who likes to seek that night should do so on the 27th.” Ubayy Ibn K’ab, may Allaah be pleased with him, said: “By Allaah, and there is no God but Him, it is during Ramadhaan – and He swore to that – and by Allaah, I know what night it is. It is the night of the 27th. Its sign is that the sun rises in the morning white and without any rays”. This is related by Muslim, Abu Daawood, Ahmad and At-Tirmithi who called it saheeh.
Praying and making supplications during the night of qadr:
Al-Bukhaari and Muslim record from Abu Hurayrah that the Prophet, sallallaahu 'alayhi wa sallam, said: “Whoever prays during the night of qadr with faith and hoping for its reward will have all of his previous sins forgiven”.
As to the supplication during the night of qadr' ,Aisha, may Allaah be pleased with her, said: "I asked the Messenger of Allaah, sallallaahu 'alayhi wa sallam, O Messenger of Allaah, if I know what night is the night of qadr, what should I say during it’? He, sallallaahu 'alayhi wa sallam, said: “Say,O Allaah, You are pardoning and You love to pardon, so pardon me.” This is related by Ahmed,Ibn Maajah, and At-Tirmithi, who called it saheeh.
[From: Fiqh us-Sunnah]