Yahya related to me from Malik from Rabia ibn Abi Abd ar-Rahmanthat if Abdullah ibn Umar arrived at the mosque and the people hadalready prayed, he would begin with the obligatory prayer and not prayanything before it. (ID)
USC-MSA web (English) reference: Book 9, Hadith 78 (ID)
Arabic reference (ID): Book 9, Hadith 409 (ID)