Sayyiduna Ubadah bin al-Samit (may Allah be pleased with him) used to lead his people in prayer. One day he came out for the morning prayer and the mu'adhdhin began to call the iqamah. Sayyiduna Ubadah bin al-Samit (may Allah be pleased with him) made him stop, then prayed witr, and after that he led them in the morning prayer.
(b) Imam Malik (may Allah have mercy on him) said: Whoever slept through witr should pray witr after Fajr, but it is not appropriate for anyone to deliberately pray witr after the rising of dawn.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4532