Musannaf Ibn Abi Shayba 3:5614

Abu Mu'awiyah narrated to us, from al-A'mash, from Ibrahim, from Abd al-Rahman ibn Yazid, who said: "Indeed, the Shaytan has a vial in which there is a blowing [substance]. When they stand for prayer, they inhale it; therefore, they were commanded at that time to perform *istinthar* (expelling water from the nose)."