Yahya related to me from Malik from Da'ud ibn al-Husayn that IbnYarbu al-Makhzumi said, "I heard Zayd ibn Thabit say, 'The middleprayer is the prayer of dhuhr.' " (ID)
App reference (ID): Book 8, Hadith 28 (ID)
USC-MSA web (English) reference: Book 8, Hadith 28 (ID)
Arabic reference (ID): Book 8, Hadith 317 (ID)