Adam Clarke's Commentary on the Bible

Verse 21 (1 Peter 2:21)

Hereunto were ye called - Ye were called to a state of suffering when ye were called to be Christians; for the world cannot endure the yoke of Christ, and they that will live godly in Christ must suffer persecution; they will meet with it in one form or other.

Christ also suffered for us - And left us the example of his meekness and gentleness; for when he was reviled, he reviled not again. Ye cannot expect to fare better than your master; imitate his example, and his Spirit shall comfort and sustain you. Many MSS. and most of the versions, instead of Christ also suffered for Us, leaving Us, etc., read, suffered for You, leaving You, etc. This reading, which I think is genuine, is noticed in the margin.

- Adam Clarke's Commentary on the Bible