Yahya related to me from Malik from Hisham ibn Urwa from hisfather that Abdullah ibn Masud said, "I do not mind if the iqama forthe subh prayer is called while I am still praying witr."
App reference: Book 7, Hadith 25
USC-MSA web (English) reference: Book 7, Hadith 25
Arabic reference: Book 7, Hadith 279