Does a person become an infidel, or is their religion forbidden to them, if they swear by saying: "My religion is forbidden to me if I do such-and-such," and then they do that, and do they remain an infidel until they perform expiation for the oath?

If someone swears, "My religion is forbidden to me if I do such-and-such," and then proceeds to do it, an expiation for breaking an oath (kaffarat yamin) becomes incumbent upon them, but they do not become an apostate by doing so. This is because their intention was not to abandon their religion, but rather to emphasize the gravity of their statement. They must repent from this oath because it is among the forbidden types of oaths. It has been reported from the Prophet, peace and blessings be upon him, that whoever swears, "I am innocent of Islam," and acts upon it, has committed a sin. This type of oath does not necessitate disbelief according to the imams; rather, it requires an expiation for breaking an oath according to Abu Hanifa and Ahmad, while nothing is required according to Malik and Al-Shafi'i.