The Prophet ﷺ said: If anyone oversleeps and misses the witr, or forgets it, he should pray when he remembers. (Using translation from Abū Dāʾūd 1431)   

قَالَ رَسُولُ اللهِ ﷺ مَنْ نَامَ عَنْ وِتْرِهِ أَوْ نَسِيَهُ فَلْيُصَلِّهِ إِذَا أَصْبَحَ أَوْ ذَكَرَهُ  

[Machine] "Have you ever thought if you had left the Fajr prayer until the sun rises, would you still pray it?" He said, "I said, what then?" He said, "Then pray it."  

أَرَأَيْتَ لَوْ تَرَكْتَ صَلَاةَ الصُّبْحِ حَتَّى تَطْلُعَ الشَّمْسُ هَلْ كُنْتَ تُصَلِّيهَا؟ قَالَ قُلْتُ فَمَهْ؟ قَالَ فَمَهْ  

[Machine] Narrated by the Prophet ﷺ that he slept through the prayer until the sun rose, then he got up and prayed.  

عَنِ النَّبِيِّ ﷺ أَنَّهُ نَامَ عَنِ الصَّلَاةِ حَتَّى طَلَعَتِ الشَّمْسُ ثُمَّ قَامَ فَصَلَّى