The Prophet ﷺ said, "When dawn breaks, the time for all night prayers and the witr has passed. So perform the witr before the break of dawn."
حدثنا محمود بن غيلان حدثنا عبد الرزاق أخبرنا ابن جريج عن سليمان بن موسى عن نافع
عن النبي ﷺ قال إذا طلع الفجر فقد ذهب كل صلاة الليل والوتر فأوتروا قبل طلوع الفجر
[Its chain of transmission is sahih] Ahmad narrated it, 2/149, 150, from Abdul-Razzaq, with the same wording. Ibn Jurayj explicitly stated that he heard it directly, as recorded by Ibn Khuzayma, 2/148, and Ahmad. It also has another route in Muslim, no. 750, and elsewhere.The hadith, "There is no witr after the dawn prayer," is daif. Ibn Hibban narrated it, no. 674, and Hakim, 1/301, 302. Qatada is in it, and he was a mudallis who narrated using ambiguous transmission phrasing.