Hair
Our hairstyle, like all external features should be appropriate and tidy, however, inner beauty (the qualities of heart) should be what Christians are known for rather than extravagant outer displays (1 Tim 2:9,10).
In the OT it was the Israelites custom for both sexes to have hair of considerable length. By the NT period it was a shame for a man to have long hair while honourable for a female (1 Cor 11:14,15). At that time a woman with short hair indicated she was an adulteress.
God has infinite knowledge of us, in fact all our hairs are numbered (Mt 10:30). The Bible also recognizes grey hair, hopefully indicating wisdom and experience as the splendour of old age and therefore to be valued (Prov 20:29).