en_tn/1pe/05/12.md

I have written to you briefly through him

Silvanus wrote the words that Peter told him to write in the letter.

what I have written is the true grace of God

"I have written about the true grace of God." Here the word "grace" refers to the gospel message, which tells of the kind things that God has done for believers. (See: rc://en/ta/man/translate/figs-metonymy)

Stand in it

The word "it" refers to "the true grace of God." Being strongly committed to this grace is spoken of as standing firmly in one place, refusing to move. Alternate translation: "Remain strongly committed to it" (See: rc://en/ta/man/translate/figs-metaphor)