Jeremiah 16:18

I will recompense their iniquity and their sin double. — A restitution, or fine, to double the amount of the wrong done was almost the normal standard of punishment under the Law of Moses (Exodus 22:4; Exodus 22:7). The words threaten accordingly a full punishment according to the utmost rigour. In Isaiah 40:2 the same thought is presented in its brighter aspect. Israel has received “double for all her sins,” and therefore, having paid, as it were, “the uttermost farthing” (Matthew 5:26), she may now hope for mercy.

The carcases... — The word may be used in scorn of the lifeless form of the dumb idols which the people worshipped, to touch which was to be polluted, as by contact with a corpse (Numbers 19:11); but it more probably points to the dead bodies of the victims that had been sacrificed to them. The phrase occurs also in a like context in Leviticus 26:30. It would appear from Isaiah 65:4 that these often included animals which by the Law were unclean: “swine’s flesh and broth of abominable things.”