The Messenger of Allah (s.a.) is quoted on page 265, Vol. 3, of al- Amin's work Miftahul Jannat, saying, "Allah has favored Friday over all other days, the month of Ramadan over all other months, and the Night of Destiny (Lailatul-Qadr) over all other nights." And Allah has favored the Holy Qur'an over all other Books which He revealed. Ibrahim, one of the companions of Imam Sadiq (a.s.), is quoted on p. 25, Vol. 94, of Bihar al-Anwar, saying that he once asked the Imam (a.s.) about how the Holy Qur'an was revealed during Lailatul-Qadr, knowing that it took more than twenty years to reveal. The Imam (a.s.) answered by saying, "The Holy Qur'an was revealed as a whole during the month of Ramadan at the Ancient House (the Kaba), then from there it was revealed along the span of (more than) twenty years." Then he cited the Messenger of Allah (s.a.) saying "The Books of Ibrahim (a.s.) were revealed on the first night of the month of Ramadan; the Torah was revealed on the sixth of the month of Ramadan; the Bible was revealed on the thirteenth of the month of Ramadan; the Psalms were revealed on the eighteenth of the month of Ramadan, and the Holy Qur'an was revealed on the twenty-fourth of the month of Ramadan." This tradition is also recorded on p. 80, Vol. 1, of al-'Ayyashi's Tafsir.
This name was used for Lailatul-Qadr because Allah Almighty determines in it for everyone all what will happen the entire next year. The "Qadr" in this sense means destiny. According to al- Qummi's Tafsir, as explained on p. 432 of its second volume, such destiny includes life and death, sustenance, abundance of crops or famine and everything good or bad. This means that Allah the Glorified and Exalted determines in this night each and every event to Occur during the next year to any and all of His creation.
Al-Majlisi quotes his father on p. 12, Vol. 94, of his own Bihar al Anwar quoting al-Nadar quoting Yahya al-Halabi quoting Ibn Maskan quoting Imam Sadiq (a.s.) saying, "During Lailalul-Qadr, the angels, the spirit, and the trusted scribes all descend to the lower heavens and write down whatever Allah decrees that year, and if Allah wishes to advance something or postpone it or add thereto, He orders the angel to erase it and replace it with whatever He decrees." On p. 182, Vol. 1, of Uyun Akhbar al-Rida, and on p. 14, Vol. 94, of Bihar al-Anwar, it is quoted that Sulayman al- Marzawi asks Imam al-Rida (a.s.), "Could you please tell us why the Chapter of Qadr was revealed?" The Imam (a.s.) said, "O Sulayman! Lailatul-Qadr is the night when Allah, the most Exalted, the most Great, decrees what will take place from one year to another of life or death, good or evil, or regarding sustenance, and whatever He then decrees is sure destiny."
It is also said that it was so named because a Book from Allah which enjoys greatness of status was revealed to a Prophet who also enjoys a great honor and prestige. Another view is that it was named so because the earth becomes straitened due to the number of angels on it. 'Qadr' according to this view, carries the meaning of straitness due to the fact that the Almighty has said "... and whoever He decides to straiten his sustenance...." and Allah knows best.
The Almighty has addressed His Messenger, our master, Muhammad (s.a.), saying, "And what will make you comprehend what Lailatul-Qadr is? Lailatul-Qadr is better than a thousand months;" (The Holy Quran, :)
There are indications that the Holy Qur'an was revealed as a whole to the Messenger (s.a.). In the Holy Qur'an, we read: "Haa, Meem. By the Book that makes (the truth) manifest, surely We revealed it on a blessed night" (The holy Quran, 44:1-3), and also, "Surely We revealed it on Lailatul-Qadr" (The Holy Quran, 98:1).
Lailatul-Qadr is a blessed night also because the Almighty brings down during it goodness, bliss, and forgiveness for His servants. One tradition of the greatest of all prophets Muhammad ibn Abdullah (s.a.) states that when Lailatul-Qadr approaches, the Almighty orders Gabriel (a.s.) to descend accompanied by a crowd of angels to the earth with a green banner. He would mount the banner atop the Ka'ba while having six hundred wings one of which is not spread except on Lailatul-Qadr; so, he would spread them during that night, and he and all other angels would greet everyone who is standing for his prayers, sitting, adoring, or reciting the Holy Qur'an. They would shake hands with them and pray the Almighty to accept their pleas, and they would continue doing so till daybreak. It is then that they would ask Gabriel: "What has the Almighty Allah done with the wishes of the believers among the nation of Muhammad (s.a.)?" He would answer, "The Almighty Allah has looked upon them on this night and forgiven them, all of them, except the following: one who is addicted to drinking, one who severs his ties with his kin, and one who is a trouble-maker."
According to the book titled al-Iqbal, the Holy Prophet (s.a) had said that the gates of heaven will be opened during Lailatul-Qadr; every devotee who performs prayers during it will receive a tree in Paradise for each prostration he makes, a tree under whose shade a rider may keep riding for a hundred years without leaving its shade. And he will receive for each rek'a a mansion in Paradise of pearls, sapphires, chrysolites and diamonds. For each verse he recites he will receive one of the crowns of Paradise. The tradition is lengthy and it contains quite a generous reward indeed.
Do you need any more clues regarding the greatness of Lailatul-Qadr? Then let us tell you that the authors of Thewab al-Amal and Bihar al-Anwar have cited the son of al-Mutawakkil quoting Imam Sadiq (a.s.): "the men whose truthfulness is not doubted even by the most skeptic scholar, saying that whoever recites Surat al-'Ankabut (The Spider) and Surat al-Rum (Romans) during the 23rd night of the month of Ramadan will secure admission into Paradise without any exception." On p. 19, Vol. 94, of Bihar al-Anwar, the Imam (a.s.) is quoted adding, "I do not fear lest Allah should record that I have committed a sin for having said s; surely these two Chapters enjoy a great status with Allah."