Question: In order to convince someone of something, it is said, for example, "So-and-so does not have a car. May I be a disbeliever if he has!" Is it considered to be an oath?
There are two rulings on this issue:
1. If one says, "So-and-so does not have a car. May I be a disbeliever if he has," the relevant person becomes a disbeliever whether that person has a car or not. One's intention does not count. That is, it is not valid.
2. If one utters something that causes disbelief with the intention of taking an oath, he is considered to have taken an oath. However, such an oath is not a Muslim's oath.