It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "Satan comes to one of you and blows near his backside, so none of you should break off the prayer until he hears a sound or notices a smell, or does that deliberately himself."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3377
Hadith Gradingمحدثین:حسن لغيره
Hadith Takhrij«حسن لغيره۔ اخرجه الدقاق في مجسله 116»