Muwatta Malik 348
موطأ مالك#348SahihYahya related to me from Malik from Nafi that Abdullah ibn Umar used to pray four rakas behind the imam at Mina, and when he prayed by himself he would pray two rakas
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Salim al-HilaliMauquf Sahih
In-book reference: 9:23