2 Timothy 2:1

Here Paul encourages Timothy to constancy and perseverance in his work: Be strong in the grace that is in Christ Jesus, Ti2 2:1. Observe, Those who have work to do for God must stir up themselves to do it, and strengthen themselves for it. Being strong in the grace that is in Christ Jesus may be understood in opposition to the weakness of grace. Where there is the truth of grace there must be a labouring after the strength of grace. As our trials increase, we have need to grow stronger and stronger in that which is good; our faith stronger, our resolution stronger, our love to God and Christ stronger. Or it may be understood in opposition to our being strong in our own strength: "Be strong, not confiding in thy own sufficiency, but in the grace that is in Jesus Christ." Compare Eph 6:10, Be strong in the Lord, and in the power of his might. When Peter promised rather to die for Christ than to deny him he was strong in his own strength; had he been strong in the grace that is in Christ Jesus, he would have kept his standing better. Observe, 1. There is grace in Christ Jesus; for the law was given by Moses, but grace and truth came by Jesus Christ, Joh 1:17. There is grace enough in him for all of us. 2.

— Matthew Henry's Concise Commentary (public domain)