The Night Prayer
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 71
وَ رُوِيَ: «أَنَّ مَنْ قَرَأَ فِي اَلْوَتْرِ بِالْمُعَوِّذَتَيْنِ وَ «قُلْ هُوَ اَللّٰهُ أَحَدٌ» قِيلَ لَهُ أَبْشِرْ يَا عَبْدَ اَللَّهِ فَقَدْ قَبِلَ اَللَّهُ وَتْرَكَ.
It is narrated : "Whoever recites in the Witr prayer the two protective chapters (Surah Al-Falaq and Surah An-Nas) and 'Qul Huwa Allahu Ahad' (Surah Al-Ikhlas), it will be said to him, 'Rejoice, O’ servant of Allah سبحانه وتعالى, for Allah سبحانه وتعالى has accepted your Witr.'"
- Ṣaḥīḥ al-Faqīh