As for those who say that puberty is indispensable, they argue that expiation atones for a sin that would otherwise be anticipated, were it not for the mercy of Allah. One who has not reached puberty is not legally accountable; the pen has been lifted from him, so his oath is not binding. Accordingly, if someone who is fourteen years and ten months old swears an oath concerning something, his oath is not binding. Indeed, even if he were to reach puberty at twelve o’clock and swear an oath at eleven, it would not be binding; whereas at one o’clock it would be binding, because in the first case he is not yet mature, while in the second he is mature.
The stronger view is that it is binding, because this falls under the category of declaratory rulings connected to their respective causes. It is true that one who is not legally accountable may not know or understand, but he does possess valid intent, as evidenced by the fact that his ritual slaughter is valid.
The second condition is that it concern the future. If it concerns the past, it is not binding. For example, if he says, “By Allah, I did not do such-and-such yesterday,” when in fact he did do it, then no expiation is due from him, because it is an oath concerning the past.
The third condition is that it concern something possible. If it concerns something impossible, it is not binding. The opposite of what is possible is what is impossible, and impossibility may be intrinsic or customary; both are alike in this regard. Thus, if someone swears an oath concerning something impossible, his oath is not binding, and no expiation is due from him—whether he swears to do it or to refrain from it—because it is impossible. No expiation is connected to what is impossible, for one who swears concerning the impossible either swears that it will not occur, in which case it is an unintentional oath, or swears that he will do it; and in this case too the oath is not binding, since it is known that, if he swears concerning it, it will not occur, so his oath concerning it serves as an affirmation of it.