Please explain what is considered tahajjud and its rulings.
In the Name of Allah, the Most Merciful and Compassionate
Tahajjud or night vigil prayer is an emphasized sunna. It is achieved by any voluntary prayer performed in the final third of the night after having slept. [Ibn ‘Abidin, Radd al-Muhtar]
If one has not slept, it is considered night worship (qiyam al-lail), not tahajjud.
Any voluntary prayer which is performed after ‘Isha is considered night worship.
The Messenger of Allah (may Allah bless him and give him peace) said, “One should perform prayer at night; even if (performed) sitting; even if to the length of milking a sheep. And any prayer performed after ‘Isha is considered of the night.” [Tabarani]
The Final Third of the Night
Even though you cannot sleep due to your occupation and wake up to perform tahajjud, the final third of the night is a blessed time in which prayers are answered, and a great reward is given.
The Messenger of Allah (may Allah bless him and give him peace) said, “Our Lord, Blessed and Exalted is He, descends (i.e., His mercy and concern descends) to the lowest heaven when the final third of the night remains and says, “Who is there to call on Me so I may answer them? Who is there to ask of Me so I may give them? Who is there to seek My forgiveness so I may forgive them?” [Bukhari]
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani
Shaykh Yusuf Weltch is a teacher of Arabic, Islamic law, and spirituality. After accepting Islam in 2008, he then completed four years at the Darul Uloom seminary in New York, where he studied Arabic and the traditional sciences. He then traveled to Tarim, Yemen, where he stayed for three years studying in Dar Al-Mustafa under some of the greatest scholars of our time, including Habib Umar Bin Hafiz, Habib Kadhim al-Saqqaf, and Shaykh Umar al-Khatib. In Tarim, Shaykh Yusuf completed the memorization of the Qur’an and studied beliefs, legal methodology, hadith methodology, Qur’anic exegesis, Islamic history, and several texts on spirituality. He joined the SeekersGuidance faculty in the summer of 2019.