By Silvanus; either Silas, Acts 15:1-41 16:1-40, whom Peter therefore here calls a faithful brother to them, that they might the more readily receive him, though a minister of the uncircumcision; or else this Silvanus was some other that had preached to them, and is therefore said to be a faithful brother to them: the former is more probable. As I suppose; this doth not signify any doubt, but rather a firm persuasion, of Silvanus's faithfulness; q.d. I reckon him faithful, having hitherto found him so: or, it may relate to the briefness of the Epistle; q.d. I suppose it will seem brief to you, as being from one that loves you, and about matters that so much concern you. Exhorting; viz. to constancy in the faith, and diligence in duty. And testifying; bearing my testimony to the truth ye have received; this the apostle witnesseth, that being more fully convinced of it, they might more constantly adhere to it. See the like phrase, Nehemiah 9:29,30 Nehemiah 13:15. That this is the true grace of God wherein ye stand; the true doctrine of God, wherein he sets forth the grace of Christ: q.d. Ye are in the right way; the doctrine ye have embraced is indeed the truth of God.
Related Commentaries of 1 Peter 5:12
1 Peter 5:12
12 By Silvanus, a faithful brother unto you, as I suppose, I have written briefly, exhorting, and testifying that this is the true grace of God wherein ye stand.