Charles Ellicott Commentary Isaiah 66:17

"They that sanctify themselves and purify themselves [to go] unto the gardens, behind one in the midst, eating swine`s flesh, and the abomination, and the mouse, they shall come to an end together, saith Jehovah." — Isaiah 66:17 (ASV)

They that sanctify themselves ... —Better, they that consecrate themselves ... As in Isaiah 65:3-4, the prophet has in mind the apostates, who gloried in mingling heathen rites with the worship of Jehovah. Such a blending of incompatible elements was, as we have seen, eminently characteristic of the reign of Manasseh. We have no trace of anything corresponding to it among the Babylonian exiles, either before or after their return. The “consecration” and “purification” are the initiatory rites of heathen mysteries, probably connected with the worship of Baal or Ashtoreth, or (as the context with its reference to gardens and swine’s flesh makes probable) with that of Thammuz. (See Note on Isaiah 64:4).

Behind one tree in the midst. —The noun “tree” is a conjectural explanation. The Hebrew text gives the “one” in the masculine, and it is explained as referring either:

1. to the Hierophant, who led the worshippers; or
2. to Thammuz, though with a contemptuous reluctance to utter the name of the false deity.

The Hebrew margin, however, gives “one” in the feminine, and this may have been intended for the Asherah—the “grove,” or phallic symbol of idolatrous worship. If we adopt the masculine and refer it to Thammuz, the word may connect with the lamentations of the Syrian maidens over Thammuz (Adonis) as over an only son (Compare Milton, Paradise Lost, Book 1).

The abomination. —The word appears in Leviticus 7:21 and Leviticus 11:11 for various kinds of unclean beasts, among which the mouse, or jerboa (still eaten by Arabs), was conspicuous (Leviticus 11:29). It is probable that all these, as well as swine’s flesh, were used in the idol-feasts. In any case, the apostate worshippers seem to have exulted in throwing off the restraints of the Mosaic law.