The second category is the vow of obstinacy and anger: that one makes his vow conditional upon something, intending thereby to prevent it, induce it, affirm a statement, or declare it false. He may then choose between fulfilling it and offering the expiation for an oath.
The author’s statement, “The second category is the vow of obstinacy and anger”: this vow is attributed to its cause—that is, the vow caused by obstinacy, meaning dispute, contention, or the like. Anger is the boiling and surging of the heart’s blood, causing a person to become agitated and make a vow. But what is its definition? He said:
“that one makes his vow conditional upon something, intending thereby to prevent it”: that is, a person makes his vow conditional upon something, intending to prevent himself from doing it. For example, he says, “If I do such-and-such, I owe Allah a vow to fast for a year.” His purpose is to prevent himself from doing it, because when he remembers the prospect of fasting for a year, he refrains.
Or a person may say to someone whom he wishes to restrain by his oath—for example, his son—“If you do such-and-such, I owe Allah a vow to fast for a year.” This too is called a vow of obstinacy and anger, for his purpose is to prevent him from doing it.
The author’s statement, “or induce it”: this is the opposite of preventing it. That is, he makes a vow in order to induce himself to act, such as when he says, “If I do not do such-and-such, my slaves are free, my properties are an endowment, and my money is a gift.” His purpose is to induce himself to act. The scholars call this a vow of obstinacy and anger, even if it involves neither obstinacy nor anger. There is no dispute over terminology: since they have called it a vow of obstinacy and anger, we say as they have said and call it what they have called it.
The author’s statement, “or affirm a statement”: for example, someone relates something to us, and we say, “This is not correct.” He then says, “I owe Allah a vow that, if it is a lie, I shall fast for a year.” Why did he say this? He said it to affirm the truth of his statement.