حَدَّثَنَا مُحَمَّدُ بْنُ بِشْرٍ حَدَّثَنَا عُبَيْدُ اللَّهِ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ قَالَ وَمَنْ صَلَّى مِنْ أَوَّلِ اللَّيْلِ فَلْيَجْعَلْ آخِرَ صَلَاتِهِ وِتْرًا فَإِنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَانَ يَأْمُرُ بِذَلِكَ
مسند امام احمد بن حنبل · Hadith 4971
It was narrated that Ibn 'Umar said: Whoever prays at the beginning of the night, let him make the Last of his prayer Witr, for the Messenger of Allah (PBUH) used to enjoin that.
Translated by Dr. Muhammad Muhsin Khan · Reviewed by Islamic University of Madinah · Published March 2020