John Gill Commentary 1 Samuel 14:7

"And his armorbearer said unto him, Do all that is in thy heart: turn thee, behold, I am with thee according to thy heart." — 1 Samuel 14:7 (ASV)

And his armourbearer said to him
Very readily and cheerfully:

do all that is in your heart ;
whatever is your pleasure, that you have a mind to do, that is upon your heart, and you are desirous of, and strongly inclined and affected to:

turn thee ;
which way you will, towards the garrison of the Philistines, or elsewhere:

behold, I am with you, according to your heart ;
I will go with you wherever you go, and do whatsoever you would have me do; I am at your command, and according to your wish and desire, and in all things subject to your will; I am as your own heart.