Lev - heart (לֵב) "Test me, O Lord, and try me, examine my heart and my mind" (Psalm 26:2). Obviously the Psalmist is not asking God for a medical examination of his myogenic muscular organ! It's from lebab (לֵבָב), meaning "the inner man," thus "lev" is figuratively used for our feelings, will, thoughts and even intellect. So here the Psalmist is actually asking God to examine every detail of his being, nothing hidden.