The Supplication of Qunoot in Witr Prayer
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 72
وَ رُوِيَ عَنْ أَبِي وَلاَّدٍ حَفْصِ بْنِ سَالِمٍ اَلْحَنَّاطِ أَنَّهُ قَالَ سَمِعْتُ أَبَا عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ يَقُولُ: «لاَ بَأْسَ بِأَنْ يُصَلِّيَ اَلرَّجُلُ رَكْعَتَيْنِ مِنَ اَلْوَتْرِ ثُمَّ يَنْصَرِفَ فَيَقْضِيَ حَاجَتَهُ ثُمَّ يَرْجِعَ فَيُصَلِّيَ رَكْعَةً.
It is narrated from Abu Walad Hafs bin Salim Al-Hannat that He said: "I heard Imam Jafar ibn Muhammad Al-Sadiq عليه السلام say, 'There is no harm if a person prays two units (rak‘ahs) of Witr prayer, then turns away to fulfil a need, and then returns to pray one unit (rak‘ah).'".
- Ṣaḥīḥ al-Faqīh, p. 70