Answered by Shaykh Faraz Rabbani
Is there any harm in offering Isha prayer after midnight? what if one is too tired and takes some rest before and offers prayers after midnight?
Answer:
Walaikum assalam wa rahmatullah,
I pray that this finds you well, and in the best of health and spirits. May Allah grant you all good and success in this life and the next.
It is somewhat disliked (makruh tanzihan) to delay Isha prayer beyond the middle of the night–the half-way between nightfall and dawn. [ Ibn Abidin, Radd al-Muhtar ] Thus, it shouldn’t be made a habit, but wouldn’t be reprehensible when very tired–on condition of being sure of getting up within the time.
And Allah alone gives success. Faraz Rabbani