Jamieson, Fausset and Brown on 1 Peter 1:16

16. Scripture is the true source of all authority in questions of doctrine and practice.

Be ye ... for I am--It is I with whom ye have to do. Ye are mine. Therefore abstain from Gentile pollutions. We are too prone to have respect unto men [Calvin]. As I am the fountain of holiness, being holy in My essence, be ye therefore zealous to be partakers of holiness, that ye may be as I also am [Didymus]. God is essentially holy: the creature is holy in so far as it is sanctified by God. God, in giving the command, is willing to give also the power to obey it, namely, through the sanctifying of the Spirit (1Pe 1:2).