'Reins' in the Bible

His archers compass me round about; He cleaveth my reins asunder, and doth not spare; He poureth out my gall upon the ground.

He hath caused the shafts of his quiver to enter into my reins.

And I will kill her children with death; and all the churches shall know that I am he that searcheth the reins and hearts: and I will give unto each one of you according to your works.