Muwatta Malik 381
موطأ مالك#381Da'ifYahya related to me from Malik from Zayd ibn Aslam that Umar ibn al-Khattab said, "You should not pray while you are holding your bowels
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Salim al-HilaliMauquf Daif
In-book reference: 9:56