In the name of God, Most Gracious, Most Merciful
Peace be upon you,
The night of Ramadan 27 (i.e., the night between the 26th and 27th fasts) is the Night of Destiny. In the lunar calendar, the day begins at sunset. So the Night of the 27th, precedes the 27th fast. The Night of Destiny is an extremely important night for Submitters to God (Muslims). It is the night in which the Holy Quran, was revealed from the Lord of the Universe to the prophet Muhammad.
Some submitters take advantage of this night to gain extra credit for the soul by spending the night commemorating God the Almighty (and doing other forms of worship like meditation or reading Quran), either in their privacy, or in a masjid with other submitters.
[Quran 97:1] We revealed it in the Night of Destiny.*
[97:2] How awesome is the Night of Destiny!
[97:3] The Night of Destiny is better than a thousand months.
[97:4] The angels and the Spirit descend therein, by their Lord’s leave, to carry out every command.
[97:5] Peaceful it is until the advent of the dawn.
*97:1 The Quran was placed into Muhammad’s soul on the 27th night of Ramadan, 13 B.H. (Before Hijrah). See also 17:1, 44:3, 53:1-18, and Appendix 28.
[Quran 39:9] Is it not better to be one of those who meditate in the night, prostrating and staying up, being aware of the Hereafter, and seeking the mercy of their Lord? Say, “Are those who know equal to those who do not know?” Only those who possess intelligence will take heed.
[Quran 17:79-80] During the night, you shall meditate for extra credit, that your Lord may raise you to an honorable rank. And say, “My Lord, admit me an honorable admittance, and let me depart an honorable departure, and grant me from You a powerful support.”
The meditation and commemoration (dhikr) are for the good of our own souls, and to draw closer to God.
[Quran 73:6-8] The meditation at night is more effective, and more righteous. You have a lot of time during the day for other matters. You shall commemorate the name of your Lord, to come ever closer and closer to Him.