Musannaf Ibn Abi Shayba 3:5622

Muhammad ibn Fudayl narrated to us, from al-A’mash, from al-Minhal ibn ‘Amr, from Qays ibn Sakan, from ‘Abdullah, who said: "Indeed, the Shaytan comes to one of you while he is in prayer and moistens his private parts until he thinks that he has broken his wudu (passed wind or urine). And he comes to him and strikes his posterior, making him think that he has broken his wudu. So do not turn away (from the prayer) until you perceive a scent or find moisture."