1 Peter 3:3-4

3 Your adornment must not be merely external — braiding the hair, and wearing gold jewelry, or putting on dresses; 4 but let it be the hidden person of the heart, with the imperishable quality of a gentle and quiet spirit, which is precious in the sight of God.

The wife’s external adornment must reflect her humble submissiveness (v. 5). And I think she can be both beautiful and submissive. But Peter emphasizes here that inner beauty is more important than outer beauty. Inner beauty will not fade away as a flower. In fact, if one is growing in the Lord it will increase in beauty, in contrast to the outward beauty of the body that will decrease with age. What is this inner beauty? Peter describes it as a gentle and quiet spirit, which is precious to God.