The prayer is invalidated by deliberately omitting the prostration that precedes the salām; if he forgets it and gives the salām, he must make it up afterward, provided only a short time has elapsed. Should lapses occur repeatedly, two prostrations suffice.
[Chapter on Voluntary Prayers]
The most emphatic of them is the eclipse prayer, followed by the rain-seeking prayer, then the tarāwīḥ, and finally the witr.
[The Witr Prayer]
Its time extends from after the ‘ishā’ prayer until daybreak. The minimum is one rakʿah (1) and the maximum is eleven, performed two by two and concluded with a single rakʿah.
The lower degree of completeness is three rakʿahs (2) with two salāms: after al-Fātiḥah he recites in the first “Glorify the Name of your Lord Most High” (Sūrah al-Aʿlā), in the second “Say: O disbelievers” (Sūrah al-Kāfirūn) (3), and in the third “Say: He is Allah, One” (Sūrah al-Ikhlāṣ).
He performs the qunūt in this prayer after bowing, as a recommended practice, saying (4):
“O Allah, guide me among those You have guided, grant me well-being among those You have granted well-being, take me into Your care among those You have taken into Your care, bless for me what You have given, and protect me from the evil You have decreed. Surely You decree, and none may decree against You; none whom You befriend can ever be abased, and none whom You oppose can ever be honored. Blessed are You, our Lord, and Exalted.” (5)