has sworn by His holiness: Holiness means God exists outside and independent of creation; his nature is entirely different from what he has created. The oath is similar to Amos 6:8; 8:7.
hooks: The Assyrians were known for their cruel treatment of war captives (see 2 Chronicles 33:11; compare 2 Kings 19:28). A stela (a stone pillar with an inscription) found in northern Syria shows the Assyrian king Esarhaddon holding cords that go through the lips of two war captives. A recent scholar has suggested that hooks referred to rings inserted into the noses of cattle to control them.