he has said. An illustration of this is when someone declares, “He is a Jew or a Christian if such-and-such is the case,” while the reality is the opposite of what he claims; in that event he is exactly as he stated—namely, a Jew or a Christian—may Allah grant us safety.

For example: a man once came to us and said, “So-and-so arrived yesterday.” We answered, “That is not correct.” He replied, “He is a Jew if he did not arrive.” It was later confirmed that the man had not arrived, and he had deliberately said, “He is a Jew.” The Messenger of Allah ﷺ made it clear that such a person is as he has described himself, meaning that he becomes a Jew or a Christian. This shows that swearing, while knowingly lying, by a religion other than Islam is one of the major sins.

If the person is truthful—he says it and what he swears to is actually the case—then this threat does not apply, although we still say to him, “If you must take an oath, swear by Allah,” in accordance with the Prophet’s ﷺ words: “Whoever has to swear, let him swear by Allah, or else remain silent.”

Likewise, if he uttered the phrase unintentionally, supposing the matter to be as he thought, and it later turned out otherwise, he does not fall under this warning. From this hadith we learn that when someone swears by Allah about something he believes to be true, and later discovers it was not as he thought, there is no sin and no expiation upon him.

For instance, a man might say, “So-and-so will arrive tomorrow—I am certain. By Allah, he will arrive tomorrow,” basing his oath on what he believes to be sure information. If the person does not arrive, no expiation is required, because the oath was made according to his honest assumption, not with deliberate falsehood.

For the same reason the Prophet ﷺ approved the statement of the man who said, “By Allah, there is no household between its two lava plains poorer than ours”—meaning between the two lava fields of Madinah there was no family poorer than his—together with