"When God says, Turn ye unto me, and I will turn unto you, one of these clauses (that which invites our return to God) evidently belongs to our will; while the other, which promises His return to us, belongs to His grace.
Here, possibly, the Pelagians think they have a justification for their opinion which they so prominently advance, that God's grace is given according to our merits."
Now the persons who hold this opinion fail to observe that, unless our turning to God were itself God's gift, it would not be said to Him in prayer, Turn us again, O God of hosts; and, You, O God, wilt turn and quicken us; and again, Turn us, O God of our salvation, — with other passages of similar import, too numerous to mention here."
Augustine, On Grace and Free Will