The kidneys, used symbolically for the inward thoughts and feelings. Psalm 7:9; Psalm 16:7; Psalm 26:2; Psalm 139:13; Proverbs 23:16; Jeremiah 12:2; Jeremiah 17:10; Jeremiah 20:12; Lamentations 3:13; Revelation 2:23 . The word translated 'reins' in Isaiah 11:5 is elsewhere translated 'loins.'