What is the expiation for swearing in anger by saying, "It is forbidden for me to enter your house and speak to you," and then entering and speaking with the person against whom the oath was made, in order to find out the reason for the quarrel?

It is not permissible to swear by other than Allah. Whoever swears by haram (that which is forbidden) or by divorce and then breaks their oath, must offer an expiation for a broken oath (kaffarat yamin). The preferred view regarding one who swears by haram is that it depends on the swearer's intention: if they intended divorce or ẓihar (a pre-Islamic form of divorce by likening one's wife to one's mother), then it is as they intended. But if they intended it as an oath or had no specific intention, then they must offer an expiation for a broken oath, which is feeding ten needy persons, or clothing them, or emancipating a slave. If they cannot find any of these, then fasting for three days. It is better to offer the expiation for ẓihar, which is emancipating a slave; if they cannot find one, then fasting for two consecutive months; if they are unable to do that, then feeding sixty needy persons.