AMBROSIASTER:
The servant sent by the Lord does what he has to do even if he is not willing, because if he does not do it he will suffer for it. Moses preached to Pharaoh even though he did not want to, and Jonah was forced to preach to the Ninevites.
ORIGEN:
The fact that he is completely free makes Paul the exemplary apostle. For it is possible to be free of immorality but a slave to anger, to be free of greed but a slave to boasting, to be free of one sin but a slave to another.
AUGUSTINE:
It is not from the one who wills nor from the one that runs but from God who has mercy that we obtain what we hope for and reach what we desire. Esau was unwilling and did not run. Had he been willing and had he run, he would have obtained the help of God who by calling him would have given him the power both to will and to run.