Hadithcore
Mishkat al-Masabih, 1258

Ibn ‘Umar reported the Prophet (ﷺ) as saying, "Make the last of your prayer at night a <i>witr</i>.” Muslim transmitted it.

وَعَنِ ابْنِ عُمَرَ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «اجْعَلُوا آخِرَ صَلَاتِكُمْ بِاللَّيْلِ وترا» . رَوَاهُ مُسلم

References1 variant
In-Book Reference
Book 4, Hadith 673