Making Haraam Upon Oneself Something Halaal

1. Saying: “It is haraam for me to eat by you,” or: “I have made that thing haraam upon me,” does not make haraam eating by that person or eating that thing.
2. However, this does constitute a Qasam.
3. By eating by that person or that particular thing, a kaffaarah [the atonement of a violated oath] will have to be given.

(Behshti Zewar)