Charles Ellicott Commentary Psalms 136:2-3

"Oh give thanks unto the God of gods; For his lovingkindness [endureth] for ever. Oh give thanks unto the Lord of lords; For his lovingkindness [endureth] for ever:" — Psalms 136:2-3 (ASV)

God of gods ... Lord of Lords— From Deuteronomy 10:17.