Abdullaah the son of Imaam Ahmad bn Hanbal said:
I asked my father about those who deny that the Jinn do enters the human body?
He said:
يا بني، يكذبون، هو ذا يتكلم على لسانه
"O my son, such are liars, it is the same Jinn (he denies) that speaks from his tongue."
- Majmuu'ul Fataawaa 24/376.