Muwatta Imam Malik Book of Tahajjud, 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."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، أَنَّ عَبْدَ اللَّهِ بْنَ مَسْعُودٍ، قَالَ مَا أُبَالِي لَوْ أُقِيمَتْ صَلاَةُ الصُّبْحِ وَأَنَا أُوتِرُ، .