"I was praying Witr, and 'Abdullah was asked: 'Is there any Witr after the Adhan?' He said: "Yes, and after the Iqamah, and he narrated that the Prophet (ﷺ) slept and missed the prayer until the sun rose then prayed.'" And the wording is that of Yahya.
Sunan an-Nasa'i Book 6, Hadith 119