What is the ruling on someone who swore, saying: "By Allah, if I do such-and-such, then upon me be ten sheep without expiation?"

This person's statement: "If I do such-and-such, then I owe ten sheep" is considered a vow of obstinacy and anger. Therefore, if he breaks it, he has the choice between fulfilling what he vowed (slaughtering the ten sheep) or offering an expiation for an oath.