Jeremiah 3:12

toward the north = toward the Northern Kingdom of Israel.

cause Mine anger to fall upon you. Hebrew cause My face, or countenance, to fall. Put by Figure of speech Metonymy (of Effect), for the anger manifested by it. Reference to Pentateuch (Genesis 4:5 , Genesis 4:6 ).

merciful = gracious, favourable.

keep. See note on "reserve", Jeremiah 3:5 .