It is narrated from Sayyiduna Abdullah bin Arqam (may Allah be pleased with him) that he said: I heard the Messenger of Allah (peace and blessings be upon him) say: "When one of you feels the need to relieve himself, let him attend to it before the prayer."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14054