Tahajjud

Tahajjud prayer is performed at night time, and it is recommended that it be performed after first going to sleep for some part of the evening. Scholars have different opinions about whether sleeping first is absolutely required or not. In Saudi Arabia during the fasting month of Ramadan, there are many people who leave the Tarawih prayers in the main mosque in a hurry so that they can go home, go to sleep, and then wake up to perform their Tahajjud prayers in the early morning.Others simply stay in the mosque and perform these optional prayers before going home.

The time for the Tahajjud prayers falls between the prayer times of the isha'a prayers and the fajr prayers. It is also recommended that the prayers be done in the last third of the night. Muslims believe that the reward is greater for those who do this prayer at a later time. (It is harder to wake up and pray early in the morning, making the person’s effort greater, resulting in a greater reward from God.)

Each prayer for a Muslim is made up with repeated actions: from standing, to bowing on the floor, to standing again is called one raka'ah. The Tahajjud prayer consists of a minimum of two raka'ah and the maximum number is unlimited.

It's reported about the Messenger of Allah (Allah bless him and give him peace) that he said: "Adhere to night prayer, for it is the habit of the righteous before you, and a means of drawing nearer to your Lord; it is an expiation for sins, and a deterrent from wrongdoing." [Tirmidhi & al-Hakim]

Abdullah ibn Amr ibn al-'As (Allah be pleased with him) relates that the Prophet Muhammad
(Allah be pleased with him) said to him, "Oh Abdullah, do not be like so-and-so, he used to pray in the night then he abandoned night prayer." [Bukhari & Muslim]

And it is reported by Aisha (Allah be pleased with her) that, "The Messenger of Allah (Allah bless him and give him peace) used to perform eleven rakats of prayer (at night), prostrating in it a prostration the length it takes any of you to read fifty verses (ayats) before raising his head." [Bukhari]

It is recommended that tahajjud be prayed during the last third of the night, but performing it at any other time is better than not performing it at all