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." (PT)
App reference (PT): Book 7, Hadith 25 (PT)
USC-MSA web (English) reference: Book 7, Hadith 25 (PT)
Arabic reference (PT): Book 7, Hadith 279 (PT)