Muwatta Malik 1685
موطأ مالك#1685SahihYahya related to me from Malik that Abu Jafar al-Qari said, "I saw Abdullah ibn Umar drink while standing
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: 49:15