Thomas Aquinas

Second, he excludes the confidence that they took from their rites of sacrifice. And first, he sets out their rejection: he that sacrifices an ox, is as if he slew a man, as if to say: their sacrifices are so abominable, as if they were doing something against the law, because they were offering them to idols; as if he should bless, praise and venerate, an idol, above: offer sacrifice no more in vain (Isa 1:13). …

Commentary on Isaiah ↗