What is the ruling regarding an imam who forgot the Witr prayer, then remembered it while leading the congregation in the Fajr prayer?

If the Imam remembers during the Fajr prayer that he has not prayed Witr, he must complete his prayer, and it is not permissible for him to interrupt it. It is recommended for him to make up the Witr prayer as an even number (two rak'ahs) during the day before Dhuhr, based on the hadith of Aisha (may Allah be pleased with her) that when the Prophet (peace be upon him) was overcome by sleep or pain, preventing him from performing the night prayer, he would pray twelve rak'ahs during the day.