Commenting on Ps. 119:18, Thomas Manton:
“We cannot merit of God. “Can a man be profitable unto God, as he that is wise may be profitable unto himself?” (Job xxii.2.) “If thou be righteous, what givest thou him? or what receiveth he of thine hand?” (Job xxxv. 7.) Whatever God doth for creatures, it freely, because he cannot be obliged or preengaged by us. In innocency, Adam could impetrare, but not mereri; obtain it by covenant, not challenge by desert. Therefore God conferreth as freely as he createth.”
There you go. Manton, a Westminster Divine, against pre-fall merit. God could bind himself and give Adam life, but Adam could not merit it. I wonder if Manton is outside the Standards?