Sunan Ibn Majah 619
سنن ابن ماجه#619Da'ifIt was narrated from Thawban that:The Messenger of Allah said: "No one among the Muslims should stand to pray when he is suppressing (the need to urinate or defecate), until he has to relieve himself
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniDaif
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih Lighairihi
Zubair Ali ZaiHasan
In-book reference: 1:353