COMMENTARY on 73:2
A. Yusuf Ali:

Translation:
Stand (to prayer) by night, but not all night,- 5755
Commentary:

5755  The Prophet was prone to austerities in the cave of Hira ', both before and after he received his mission, spending days and nights in prayer and contemplation. See C. 29. Midnight and after-midnight prayers have technically received the name of Tahajjud. See also verse 20 below; also 17:79. (R).