Narrator:Ali
وَعَنْ عَلِيِّ بْنِ أَبِي طَالِبٍ - رضى الله عنه - قَالَ : { لَيْسَ اَلْوِتْرُ بِحَتْمٍ كَهَيْئَةِ اَلْمَكْتُوبَةِ , وَلَكِنْ سُنَّةٌ سَنَّهَا رَسُولُ اَللَّهِ - صلى الله عليه وسلم -} رَوَاهُ النَّسَائِيُّ وَاَلتِّرْمِذِيُّ وَحَسَّنَهُ وَالْحَاكِمُ وَصَحَّحَهُ . 1
1 - رواه النسائي ( 3 / 229 ) ، والترمذي ( 453 و 454 ) ، والحاكم ( 1 / 300 ) . وقال الترمذي : حديث حسن .
Narrated 'Ali bin Abu Talib (RA):
The Witr prayer is not obligatory as the prescribed prayer is [i.e. the five daily prayers], but it is a Sunnah which was established by the practice of Allah's Messenger (ﷺ). [at-Tirmidhi and an-Nasa'i reported it, who graded it Hasan (good). al-Hakim graded it Sahih (authentic)].
Reported by At-Tirmidhi (No. 454), An-Nasa’i (No. 1676) and Ahmad (No. 617, 722, 747, 883, 1157, 1169). Cited in Bulugh al-Maram (No. 371).