Ibn Al Qayyim (raḥimahullāh) said,

“There is variance in his (Aḥmad’s) statement with regards to delaying the Tarāwīḥ until the latter part of the night. It is reported from him, ‘If they delay the Qiyām until the last part of the night, then there is no harm’ just like ʿUmar (radi-Allāhu ʿanh) said that the duration which they sleep after praying it is better (for performing it), and that’s because the Qiyām takes place after sleeping. Allāh The Most Hight said,

إِنَّ نَاشِئَةَ ٱلَّیۡلِ هِیَ أَشَدُّ وَطۡـࣰٔا وَأَقۡوَمُ قِیلًا
Verily, the rising by night is very hard and most potent and good for governing (the soul), and most suitable for (understanding) the Word (of Allah). [Al-Muzzammil: 6]

And Abū Dāwūd reported from him, ‘Qiyām is not to be delayed until the last part of the night, the practice of the Muslims is more beloved to me’ and his indication is towards the action of the Companions. And the statement of ʿUmar (radi-Allāhu ʿanh) is understood to be an encouragement to pray during the last part of the night so that they pray their Qiyām until the last part of the night, not that they delay it.”

Source: ‘Badāʾiʿ Al-Fawāʾid’ Vol.4, Pg.918

Translated by: Zubayr bin Muḥammad ʿAbbāsī