Sforno on Leviticus 22:18/ספורנו על ויקרא כ״ב:י״ח

1אשר יקריב קרבנו, after the Torah had addressed the priests, who offer the sacrifices on the altar as well as their status of sanctity, it now discusses rules applying to the offerings themselves., saying that the following applies to לכל נדריהם ולכל נדבותם, even these offerings were voluntary offerings as opposed to mandatory offerings, and I might have thought that any such offering, even of a blemished animal, would be gratefully accepted by G’d, seeing the individual in question was under no obligation to offer any sacrifice at this time, the Torah states flatly that this is not so. The author, quoting Maleachi 1,5 as proof that one would not dare offer a gift to a human ruler that was less than perfect, how much less would one dare to do this “for” G’d, concludes that there must have been people in his time guilty of mistaking what is expected of them and offering inferior animals as sacrifices.