What is the ruling on one who says to his wife, "You are thrice divorced" or "You are divorced, divorced, divorced" without intending a specific number, and what is the source of the fatwa and the adopted madhhab?

It has been authentically reported from the Prophet (peace be upon him) that "Three matters, their seriousness is serious, and their jest is serious: marriage, divorce, and a return [to marital relations after a revocable divorce]." Scholars have agreed that if a sane, adult person utters a clear pronouncement of divorce, they are held accountable for it, and their claim of jest or lack of intention to divorce will not benefit them. If he says, "You are divorced for the fullness of the world," and intends three [divorces], then three occur. If he intends nothing or intends one, then one occurs.