1 Peter 3:6

as Sarah obeyed Abraham, calling him lord: whose children ye are now, if ye do well, and are not put to fear by any terror.

As Sarah obeyed Abraham ... It should not be thought that Sarah's obedience to Abraham was in any sense Servility. On one occasion she ordered Abraham to "Cast out the bondwoman and her son," a "request" that sorely grieved and distressed Abraham; but he obeyed her, God himself commanding Abraham to do it (Genesis 20:10-12). Nevertheless, there was the utmost respect and honor accorded her husband by the noble Sarah.

Calling him lord ... The significance of Sarah's doing this lies in the fact that this is what she called him in her own heart, not merely when others might hear her. The real test of what one is, or what one thinks, lies in the content of what they say to themselves, not in what they might say to others (Genesis 18:12).

Whose children ye are ... Paul extensively developed the thought of Christians being the children of Abraham, a principle given by Christ himself (John 8:39ff); and this is a further extension of the same truth. Being sons of Abraham, as all Christians are (Galatians 3:29), they are also children of Sarah, Abraham's wife.

If ye do well ... This qualifier stands over against all Christian privilege. The thing that disqualified the Jews of Jesus' day as true sons of Abraham was disobedience; and the Christian must accept the application of the same principle to the members of the new Israel. If they do not do well, they shall become, like the disobedient Jews of Jesus' day, "sons of the devil" (John 8:44).

And are not put in fear by any terror ... The sentiment here is that of Proverbs 3:25, which seems to have been a chapter that Peter was very familiar with; for he quoted it again in 1 Peter 5:5. "Peter is apparently thinking of some attempt (by a pagan husband perhaps?) to scare a woman out of her Christian faith."[8] Justin Martyr relates the narrative of a certain woman who accepted Christianity and turned from a wicked and dissolute life, but whose husband continued stubbornly in the old ways; and after prolonged abuse, and even abandonment, she legally divorced him. However, her husband, being restrained by a court order from harming his wife, persecuted to death her Christian teacher.[9]

[8] Archibald M. Hunter, op. cit., p. 123.

[9] Justin Martyr, The Second Apology in the Ante-Nicene Fathers, Vol. I (Grand Rapids, Michigan: Wm. B. Eerdmans Publishing Company, n.d.), p. 188.