It is unanimously agreed that one may perform voluntary prayers while seated even when able to stand.

He should conclude his night worship with the witr, for the Prophet used to make the last of his prayers at night an odd-numbered witr and instructed the community to do the same in numerous hadiths.

If someone misses his tahajjud during the night, it is recommended that he make it up before ẓuhr, in light of the report: “Whoever sleeps through his nightly portion, or part of it, and then recites it between the dawn prayer and the noon prayer, it will be written for him as though he had recited it during the night.”

O Muslim, do not deprive yourself of a share in the night vigil, even if it is a small amount that you maintain regularly, so that you may attain the reward of those who stand in prayer and seek forgiveness before dawn. A little may well lead you to much, and Allah does not cause the reward of the doers of good to be lost.