He will turn again, and have compassion upon us. The verb "turn again," joined with another verb, often denotes the repetition of an action, as in Job 7:7; Hosea 14:8, etc.; so here we may translate simply, "He will again have compassion."
He will subdue; literally, tread underfoot. Sin is regarded as a personal enemy, which by God's sovereign grace will be entirely subdued. So, according to one interpretation, sin is personified (Genesis 4:7; comp.
Psalms 65:8). Cast all their sins into the depths of the sea. Thou wilt blot out and bury completely and forever, as once thou didst overwhelm the Egyptians in the Red Sea (Exodus 15:1, Exodus 15:4, Exodus 15:10, Exodus 15:21).
The miraculous deliverance of the Israelites at the Exodus is a type of the greater deliverance of the true Israelites in Christ (Psalms 103:12; 1 John 1:7; comp. Isaiah 43:25).