(Exodus 22:24) begins: "Im you lend money to My people." The word "im" typically means "if" — suggesting optionality. But Rabbi Yishmael taught that this is one of the rare cases where "im" means "when" — making the instruction mandatory. Lending money to the poor is not optional. It is an obligation.
Rabbi Yishmael identified this as one of three exceptional uses of "im" in the Torah. In each case, what appears to be a conditional statement is actually a mandatory command. The key to identifying these exceptions is finding companion verses that use imperative language about the same subject.
The second exception is (Leviticus 2:14): "And im you offer a meal-offering of first-fruits." This sounds optional — "if" you happen to bring first-fruits. But a companion verse uses mandatory language: "You shall bring the meal-offering of your first-fruits." The imperative form confirms that the "if" is really a "when."
Rabbi Yishmael's three exceptions transform three apparent permissions into three binding duties. You must lend money to the poor. You must bring first-fruits. In each case, the Torah's use of "if" is a linguistic convention, not an actual condition. The obligation exists regardless of the speaker's intention. This teaching had profound social consequences: lending to the needy was not charity at the lender's discretion but a commandment that every Israelite was bound to fulfill.