What are the conditions for performing the Qiyam al-Layl prayer? And is it obligatory to sleep before performing it, or is it permissible to perform it by waking up at the time of Sahar and before the last third of the night? And is performing the prayer before sleeping considered to achieve the same reward?

For the validity of the Night Prayer, the same conditions as for other prayers apply: purity, covering the 'awrah, facing the Qiblah, and the entry of its time, which begins after the 'Isha prayer and extends until the break of dawn. Neither sleeping before nor after it is a condition. Its best time, for those who are able, is the last third of the night.