Zaid b. Aslam reported God’s Messenger as saying, “If any of you oversleeps and misses his witr, he should observe it in the morning.” Tirmidhi transmitted it in mursal form.
Reported by At-Tirmidhi (No. 466). Cited in Mishkat al-Masabih (No. 1268).
"Whoever forgets a prayer should perform it as soon as he remembers it; there is no expiation for it except that: {and establish prayer to remember me.} [Surat Tā-ha: 14]"
Abu Sa‘īd al-Khudri (may Allah be pleased with him) reported the Prophet (may Allah's peace and blessings be upon him) said: "If anyone sleeps before praying Witr or forgets it, let him pray it once he remembers it."