Is it permissible to make a vow conditional on marrying a specific person, and must it be fulfilled after the wish comes true?

The vow (nadhr (definition)) is not established by saying, "I will fulfill a vow," but rather by a wording that indicates commitment, such as: "For Allah is upon me such-and-such," or "I vowed if so-and-so marries me..." A conditional vow does not become obligatory to fulfill unless the condition is met. If the vow is ambiguous, then, according to the majority of scholars, an expiation for breaking an oath (kaffarat yamin (definition)) is required. Whoever does not fulfill a vow despite being able to do so is sinful, and vowing is disliked (makrooh).