John Calvin Commentary Hebrews 13:21

"make you perfect in every good thing to do his will, working in us that which is well-pleasing in his sight, through Jesus Christ; to whom [be] the glory for ever and ever. Amen." — Hebrews 13:21 (ASV)

To do his will, etc. He now gives a definition of good works by laying down God’s will as the rule. He thus intimates that no works are to be considered good unless they are agreeable to the will of God, as Paul also teaches us in Romans 12:2 and in many other places. Let us then remember that it is the perfection of a good and holy life when we live in obedience to His will. The clause that next follows is explanatory: working (or doing) in you what is well pleasing in his sight. He had spoken of that will which is made known in the Law; he now shows that it is futile to impose on God what He has not commanded, for He values the decrees of His own will far more than all the inventions of the world.

Through Jesus Christ, etc. This may be explained in two ways — “Working through Jesus Christ,” or, “Well-pleasing through Jesus Christ.” Both senses are suitable. For we know that the Spirit of regeneration and also all graces are bestowed on us through Christ. It is also certain that since nothing can proceed from us absolutely perfect, nothing can be acceptable to God without that pardon which we obtain through Christ. Thus it is that our works, which carry the scent of Christ’s grace, emit a sweet fragrance in God’s presence, while otherwise they would have a foul smell. I am disposed to include both meanings.

To whom be glory, etc. This I refer to Christ. And as he here ascribes to Christ what uniquely belongs to God alone, he thereby bears clear testimony to His divinity. However, if anyone prefers to explain this as referring to the Father, I do not object, though I embrace the other interpretation as being the most obvious.