God loathes even the sacrifices of the wicked (Isa 1:11; Pro 15:8; Pro 28:9).
is as if - Lowth not so well omits these words: “He that killeth an ox (presently after) murders a man” (as in Eze 23:39). But the omission in the Hebrew of “is as if” - increases the force of the comparison. Human victims were often offered by the heathen.
dog’s neck - an abomination according to the Jewish law (Deu 23:18); perhaps made so, because dogs were venerated in Egypt. He does not honor this abomination by using the word “sacrifice,” but uses the degrading term, “cut off a dog’s neck” (Exo 13:13; Exo 34:20). Dogs as unclean are associated with swine (Mat 7:6; 2Pe 2:22).
oblation - unbloody: in antithesis to “swine’s blood” (Isa 65:4).
burneth - Hebrew, “he who offereth as a memorial oblation” (Lev 2:2).
they have chosen - opposed to the two first clauses of Isa 66:4 : “as they have chosen their own ways, etc., so I will choose their delusions.