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."
Sunan Ibn Majah Book 1, Hadith 353
← Previous Hadith "The Messenger of Allah said, 'No one of you should stand to pray when he feels some discomfort (because of needing to urinate or defecate).'"

Sunan Ibn Majah Book 1, Hadith 352 Next Hadith → She went to the Messenger of Allah and complained to him about bleeding. The Messenger of Allah said: "Rather that is a vein, so look and see when your period comes, then do not perform the prayer. When the period is over, then purify yourself and perform the prayer between one period to the next."

Sunan Ibn Majah Book 1, Hadith 354