Abu Kabsha al-Anmari told that Allah's Messenger ﷺ had himself cupped on the top of his head because of the poisoned sheep.* Ma'mar said

I had myself cupped like that in the middle of my head for a reason other than poison and suffered some loss of memory till I was recommended to use Fatihat al-Kitab in the prayer. Razin transmitted it. * An attempt was made to poison the Prophet (ﷺ) after the conquest of Khaibar in 7 A.H., but when he had taken a mouthful of the poisoned meat he spat it out realizing that it was poisoned.