Augustine of Hippo

We should not suppose, because he said, "For it is God that works in you both the willing and the doing," that he has taken away free will. For if that were so he would not have said above "Work out your own salvation with fear and trembling." For when he bids them work, it is agreed that they have free will. But they are to work with fear and trembling so that they will not, by attributing the good working to themselves, be elated by the good works as though they were their own.