Re: Why Hijab
Verse 24:31
Ahmed Raza Khan: Mohammed Aqib Qadri:
And command the Muslim women to keep their gaze low and to protect their chastity, and not to reveal their adornment except what is apparent, and to keep the cover wrapped over their bosoms; and not to reveal their adornment except to their own husbands or fathers or husbands’ fathers, or their sons or their husbands’ sons, or their brothers or their brothers’ sons or sisters’ sons, or women of their religion, or the bondwomen they possess, or male servants provided they do not have manliness, or such children who do not know of women’s nakedness, and not to stamp their feet on the ground in order that their hidden adornment be known; and O Muslims, all of you turn in repentance together towards Allah, in the hope of attaining success. (It is incumbent upon women to cover themselves properly.)
Yusuf Ali:
And say to the believing women that they should lower their gaze and guard their modesty; that they should not display their beauty and ornaments except what (must ordinarily) appear thereof; that they should draw their veils over their bosoms and not display their beauty except to their husbands, their fathers, their husband’s fathers, their sons, their husbands’ sons, their brothers or their brothers’ sons, or their sisters’ sons, or their women, or the slaves whom their right hands possess, or male servants free of physical needs, or small children who have no sense of the shame of sex; and that they should not strike their feet in order to draw attention to their hidden ornaments. And O ye Believers! turn ye all together towards Allah, that ye may attain Bliss.
Pickthal:
And tell the believing women to lower their gaze and be modest, and to display of their adornment only that which is apparent, and to draw their veils over their bosoms, and not to reveal their adornment save to their own husbands or fathers or husbands’ fathers, or their sons or their husbands’ sons, or their brothers or their brothers’ sons or sisters’ sons, or their women, or their slaves, or male attendants who lack vigour, or children who know naught of women’s nakedness. And let them not stamp their feet so as to reveal what they hide of their adornment. And turn unto Allah together, O believers, in order that ye may succeed.
Yusuf Ali mentions beauty in general but the the common factor among these translations is adornment or ornament. Hair is not an ornament. You cannot reveal any body adornment (such as a belly adorment which was probably worn at the time) other than what is apparent such as ear-rings, etc.
I don’t agree with everything this scholar says but still worth having a look at: