The following is the results of your search for reins.
Reins: The kidneys, the supposed seat of the desires and affections; used
metaphorically for "heart." The "reins" and the "heart" are often
mentioned together, as denoting the whole moral constitution of man
(Psalms 7:9; 16:7; 26:2; 139:13; Jeremiah 17:10) etc.