Mark 9:17

17 And one of the crowd answered Him, “Teacher, I brought You my son, possessed with a spirit which makes him mute;

Mark 9:18

18 and ¹whenever it seizes him, it ²slams him to the ground and he foams at the mouth, and grinds his teeth and ³becomes rigid. I told Your disciples to cast it out, and they could not do it.”