The Messenger of Allah ﷺ said, "Pray witr before morning comes."
حدثنا الحسن بن علي الخلال حدثنا عبد الرزاق أخبرنا معمر عن يحيى بن أبي كثير عن أبي نضرة
قال رسول الله ﷺ أوتروا قبل أن تصبحوا
No references are available.
Muslim also narrated it in the Book of the Prayer of Travelers, in the chapter on the night prayer being performed two by two with Witr being one rakat at the end of the night, hadith no. 754, from the hadith of Muamar bin Rashid, with the same chain.