Philippians 1:6 (BSB)

being confident of this, that He who began a good work in you will carry it on to completion until the day of Christ Jesus.

From Philippians 1. Also in the ESV.

Commentary on Philippians 1:6

• John Calvin (Reformed), Calvin's Commentaries on Philippians 1:6: 6 Persuaded of this very thing. An additional ground of joy is furnished in his confidence in them for the time to come. “Qu’il se confioit d’eux qu’ils perseuereroyent de reste de leur vie;” — “That he had confidence in them that they would persevere during the remainder of their life.” But some one will say, why should men dare to assure themselves for to-morrow...
• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Philippians 1:3-6: The apostle proceeds after the inscription and benediction to thanksgiving for the saints at Philippi. He tells them what it was he thanked God for, upon their account. Observe here, I. Paul remembered them: he bore them much in his thoughts; and though they were out of sight, and he was at a distance from them, yet they were not out of his mind: or...
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Philippians 1:6: Being confident of this very thing,.... The reason of his thanksgiving, and of his making request with joy continually on the behalf of this church, was the confidence and full persuasion he had of this same thing, of which he could be as much assured as of any thing in the world: that he which hath begun a good work in you, will perform it...
• Albert Barnes (Presbyterian), Barnes' New Testament Notes on Philippians 1:6: Verse 6. Being confident. This is strong language. It means to be fully and firmly persuaded or convinced. Part. Mid. voice from πειθω--to persuade. Comp. : "Neither will they be persuaded, though one rose from the dead;" that is, they would not be convinced. . It means here that Paul was entirely convinced of the truth of what he said.