The LORD hath sworn by the excellency of Jacob, Surely I will never forget any of their works.
The Lord hath sworn by the excellency of Jacob - i:e., by Himself, in whom Jacob's seed glory (Maurer); or, by the spiritual privileges of Israel, the adoption of Israel as His special people (Calvin), the temple, and its Shekinah-symbol of His presence. Compare Amos 6:8, "I abhor the excellency of Jacob," where it means Yahweh's temple (cf. Amos 4:2).
Surely I will never forget - I will not pass by without punishing (Amos 8:2; Hosea 8:13; Hosea 9:9).