Is the end of the Witr prayer at the beginning of the Fajr adhan or at its end?

Question:
From Abdulaziz ibn Abdullah ibn Baz to the honorable brother (M. A.) (may Allah preserve him from all evil), amen.
Peace be upon you, and Allah's mercy and blessings. As for what follows:
Your noble letter dated 16/2/1409 AH has reached us, may Allah connect you to the rope of guidance and success. The questions it contained were known, and here is their text and answer:
Q: Is the end of the Witr prayer at the beginning of the adhan—the Fajr adhan—or at the end of the adhan? And if one sleeps through it, is it made up? And how?

Answer:
It is prescribed for every believing man and woman to perform Witr every night, and its time is between the 'Isha' prayer and the dawn; for it is established in the two Sahihs from Ibn 'Umar (may Allah be pleased with them both) from the Prophet (peace and blessings be upon him) that he said: .
And Muslim narrated in his "Sahih" from Abu Sa'id al-Khudri (may Allah be pleased with him) from the Prophet (peace and blessings be upon him) that he said: .
And Imam Ahmad, Abu Dawud, and al-Tirmidhi narrated it, and al-Hakim graded it as authentic, from Kharijah ibn Hudhafah (may Allah be pleased with him) from the Prophet (peace and blessings be upon him) that he said: We said: O Messenger of Allah, what is it? He said: .
The hadiths in this chapter are numerous, and they indicate that Witr ends with the dawn. If the one praying does not know the dawn has appeared, he relies on the mu'adhdhin known for verifying the time. If the mu'adhdhin who verifies the time of Fajr calls the adhan, the Witr is missed. As for the one who calls the adhan before Fajr, the Witr is not missed by his adhan, nor does it forbid the fasting person from eating and drinking, nor does the time for the Fajr prayer enter with it; for the Prophet (peace and blessings be upon him) said: It is agreed upon that it is authentic.
And Ibn Umm Maktum was a blind man who did not call the adhan until it was said to him: "The dawn has come, the dawn has come."
And by what we have mentioned, it becomes clear to you that the time for Witr ends with the first adhan if the mu'adhdhin is verifying the dawn in his adhan. But if the mu'adhdhin calls the adhan and the Muslim is in the last rak'ah, he completes it due to uncertainty about the dawn appearing merely with the adhan, and there is no harm in that, if Allah wills.
And whoever misses the Witr, it is prescribed for him to pray his usual amount during the day, but he makes it even by adding a rak'ah. So if his usual is three, he prays four; and if his usual is five, he prays six; and so on, he says the taslim from every two; for it is established in "Sahih Muslim" from A'ishah (may Allah be pleased with her) that she said: .
And his (peace and blessings be upon him) predominant habit was to perform Witr with eleven rak'ahs. So if he was prevented from it by illness or sleep, he prayed twelve rak'ahs, as A'ishah (may Allah be pleased with her) said, saying the taslim from every two; for it is established from A'ishah (may Allah be pleased with her) that she said: , it is agreed upon that it is authentic. And for the saying of the Prophet (peace and blessings be upon him): It was narrated by Imam Ahmad and the people of the Sunan with a sound chain from the hadith of Ibn 'Umar (may Allah be pleased with them both), and its original is in the two Sahihs with the wording: as mentioned at the beginning of this answer. And Allah is the guarantor of success.