Prayers(Salah) After Isha as Tahajjud : Mufti Taqi Usmani’s Practical Advice for Night Worship (Malfoozat of Shaykh al-Islam Hazrat Maulana Mufti Muhammad Taqi Usmani)
It was advised that Salat al-Layl (the night prayer) is not obligatory, but it is a significant means of attaining closeness to Allah. Allah has made it very easy for us to perform it. In Mu’jam Tabarani, there is a Marfu’ Hadith in which the Prophet Muhammad (peace be upon him) is reported to have said that any prayer (Salaah) performed after the Isha prayer is considered Salat al-Layl.
Therefore, if someone is unable to wake up during the last part of the night, they can at least perform a few rak’ahs after Isha and before Witr with the intention of Salat al-Layl.
Then, if they do wake up in the last part of the night, that is excellent, but if they do not, they will not miss out on the blessings of Salat al-Layl.
(Khutbat-e-Ramadan, Page 293)
This Malfooz is selected by Dr. Faisal Sahib.