1 Corinthians 11:4-5
“Every man praying or prophesying having his head covered, dishonors his head. But every woman praying or prophesying with her head unveiled dishonors her head.”
For there were, as I said, both men who prophesied and women who had this gift at that time, as the daughters of Philip, as others before them and after them: concerning whom also the prophet spoke of old: “your sons shall prophesy, and your daughters shall see visions.”
Well then: the man he compels not to be always uncovered, but only when he prays. “For every man,” says he, “praying or prophesying, having his head covered, dishonors his head.” But the woman he commands to be at all times covered. Wherefore also having said, “Every woman that prays or prophesies with her head unveiled, dishonors her head,” he stayed not at this point only, but also proceeded to say, “for it is one and the same thing as if she were shaven.” But if to be shaven is always dishonorable, it is plain too that being uncovered is always a reproach. And not even with this only was he content, but added again, saying, “The woman ought to have a sign of authority on her head, because of the angels.” He signifies that not at the time of prayer only but also continually, she ought to be covered. But with regard to the man, it is no longer about covering but about wearing long hair, that he so forms his discourse. To be covered he then only forbids, when a man is praying; but the wearing long hair he discourages at all times. Wherefore, as touching the woman, he said, “But if she be not veiled, let her also be shorn;” so likewise touching the man, “If he have long hair, it is a dishonor unto him.” He said not, “if he be covered” but, “if he have long hair.” Wherefore also he said at the beginning, “Every man praying or prophesying, having any thing on his head, dishonors his head.” He said not, “covered,” but “having any thing on his head;” signifying that even though he pray with the head bare, yet if he have long hair, he is like to one covered. “For the hair,” says he, “is given for a covering.”
Source: Homilies on First Corinthians (New Advent)