1 Corinthians 11:14

Doth not even nature itself teach you, that, if a man have long hair, it is a shame unto him?

Cross-reference

In 1 Cor 11:4, a man covering his head dishonors his head—directly related to the same discussion on male appearance in worship.

In 1 Cor 14:35, Paul restricts women speaking in church—same concern for gender-appropriate conduct in worship as here.

In Ezekiel 44:20, priests are told not to let their hair grow long—parallel to Paul's view that long hair on men is disgraceful.