It wasnarrated that Abu Sa'eed said:
"The Messenger of Allah (ﷺ)said: 'Whoever sleeps and misses Witr, or forgets it, let him prayitwhen morning comes, or when he remembers.'" (PT)
English reference (PT): Vol. 1, Book 5, Hadith 1188 (PT)
Arabic reference (PT): Book 5, Hadith 1244 (PT)