Which remain among the graves, and lodge in the monuments, which eat swine's flesh, and broth of abominable things is in their vessels;
Which remain among the graves - namely, for purposes of necromancy, as if to hold converse with the dead (Isaiah 8:19-20: cf. Mark 5:3); or, for the sake of purifications, usually performed at night among sepulchres, to appease the manes (Maurer).
And lodge in the monuments - Hebrew, 'pass the night in hidden recesses' ( banªtsuwriym (H5341)); either the idol's inmost shrines ('consecrated precincts') (Horsley), where they used to sleep, in order to have divine communications in dreams (Jerome and Vulgate); or better, on account of the parallel "graves," sepulchral caves. So the Septuagint, Chaldaic, Arabic, and Syriac (Maurer).
Which eat swine's flesh. To eat it at all was contrary to God's law (Leviticus 11:7); but it much increased their guilt that they ate it in idolatrous sacrifices (cf. Isaiah 66:17). Varro ('Re Rust,' 2: 4) says, that swine were first used in sacrifices: the Latins sacrificed a pig to Ceres; it was also offered on occasion of treaties and marriages.
And broth of abominable (things is in) their vessels - so called from the 'pieces' (margin) or fragments of bread over which the broth was poured (Gesenius): such broth, made of swine's flesh, offered in sacrifice, was thought to be especially acceptable, to the idol, and was used in magic rites. Or, 'fragments (pieces) of abominable foods,' etc. This fourth clause explains more fully the third, as the second does the first (Maurer).
Is in - rather, literally, 'is their vessels;' i:e., constitute their vessels' contents. The Jews, in our Lord's days, and ever since the return from Babylon, have been free from idolatry. Still the imagery from idolatrous abominations, as being the sin most loathsome in God's eyes, and that most prevalent in Isaiah's time, is employed to describe the foul sin of Israel in all ages, culminating in their killing Messiah, and still rejecting Him. For before God "rebellion is as the sin of witchcraft, and stubbornness is as iniquity and idolatry" (1 Samuel 15:23).