Is it permissible to complete the Witr prayer after the Fajr Adhan if I intended to pray three rak'ahs, and I said the taslim after the second rak'ah during the tashahhud, then the Fajr Adhan was called before performing the third rak'ah?

If a worshiper intends to pray two rak'ahs followed by one rak'ah for Witr, and the muezzin gives the call to prayer while he is reciting the Tashahhud, he should complete his prayer and make the taslim, then pray the single rak'ah of Witr. It is permissible to make up the Witr prayer after the dawn adhan and before the Fajr prayer, and this was done by many of the Salaf. And whoever sleeps through his Witr or forgets it should pray it when he wakes up or remembers, based on the Prophet's (peace and blessings be upon him) saying: "Whoever sleeps through his Witr or forgets it, let him pray it when he wakes up or remembers." He should not stand for a third rak'ah before the taslim, due to the prohibition of praying Witr with three rak'ahs in a manner resembling Maghrib prayer.