New Defender's Study Bible Notes
3:22 compassions fail not. Jeremiah recalled that God had promised that the people of Israel would be preserved and eventually restored (Jeremiah 31:37-40; 46:28; etc.), though all he could see at the moment was devastation.
3:23 great is thy faithfulness. God is faithful to His Word, even when we are not faithful and forget His Word. Note II Timothy 2:13.