for it is God who works in you, both to will and to work for his good pleasure.
13 It is God that worketh. This is the true engine for bringing down all haughtiness — this the sword for putting an end to all pride, when we are taught that we are utterly nothing, and can do nothing, except through the grace of God alone. I mean supernatural grace, which comes forth from the spirit of regeneration.
I. He exhorts them to diligence and seriousness in the Christian course: Work out your own salvation. It is the salvation of our souls (Pe1 1:9), and our eternal salvation (Heb 5:9), and contains deliverance from all the evils sin had brought upon us and exposed us to, and the possession of all good and whatsoever is necessary to our complete and final happiness.
Commenting on Philippians 2:12-13
For it is God which worketh in you,.... Which is both an encouragement to persons conscious of their own weakness to work, as before exhorted to; see Hag 2:4; and a reason and argument for humility and meekness, and against pride and vain glory, since all we have, and do, is from God; and also points out the spring, principle, and foundation of all good...