Muwatta Malik Book 7, Hadith 25
Yahya related to me from Malik from Hisham ibn Urwa from his
father that Abdullah ibn Masud said, "I do not mind if the iqama for
the subh prayer is called while I am still praying witr."
Yahya related to me from Malik that he had heard that Abdullah ibn Abbas and Ubada ibn as-Samit and al-Qasim ibn Muhammad and Abdullah ibn Amir ibn Rabia had all prayed witr after the break of dawn.
Yahya related to me from Malik that Yahya ibn Said said, ''Ubada ibn as-Samit used to lead the people in prayer. One day he came out for subh and the muadhdhin began to give the iqama for the subh prayer Ubada silenced him, prayed witr and then led them in subh."