When is the making up of the witr prayer?

The questioner : It is reported in "Musnad al-Imam Ahmad" from Abu Sa'id, traced back to the Prophet (peace and blessings be upon him): This hadith, and another hadith from Qays ibn 'Amr, that he went out for the dawn prayer and found the Prophet (peace and blessings be upon him) in the dawn prayer, having not performed the two rak'ahs of Fajr. The Prophet (peace and blessings be upon him) passed by him and said: . He informed him, and the Prophet (peace and blessings be upon him) remained silent and said nothing.
In "Al-Fath al-Rabbani," after explaining it, it was said: "In this chapter, from Ahmad and al-Tabarani in "Al-Awsat," from 'A'ishah: "The Messenger of Allah (peace and blessings be upon him) would wake up and complete [the witr]." Its chain of narration is good. And from Abu al-Darda' in al-Hakim and al-Bayhaqi: "I would often see the Messenger of Allah (peace be upon him) performing witr while the people had already stood up for the dawn prayer." Al-Hakim graded it as authentic. What is your opinion, O Shaykh?

The Shaykh : I see that both matters are permissible; that is, one who forgets the witr or sleeps through it is treated exactly like the obligatory prayer; in that he is ordered to perform it when he wakes up from his sleep, or when he remembers what he had forgotten of the witr.

The questioner : Even if the dawn has already appeared?

The Shaykh : Yes, unless it causes him to miss, for example, the congregational prayer; that is a separate matter.