The veil, or hijab, is not Islamic in origin. Islam adopted the practice directly from the Byzantine Christians and the Iranian Zoroastrians. It wasn’t even practiced in the Caliphate until the late second century of the Islamic era, with the advent of the Abbasid dynasty from Khorasan, an Iranian territory once known as Parthia, in 750 BCE. The practice was adopted from the Roman Empire, where Byzantine women in wealthy families were veiled and usually shut away as there Greek and Roman predecessors were before them, as well as being brought from Iran, where high-born families had adopted the practice directly from Assyria, the first culture to introduce the veil for women.
The practice of women wearing the veil began in ancient Assyria where it was a mark of status for high-born women, who were usually shut away. After Cyrus the Great’s conquest of Mesopotamia, high-born women in Iran adopted the practice, and from there it spread first to Greece and later to Rome.
In the West, the enforcement of the tradition became stricter with the advent of Christianity, when it spread to the lower classes. This was directly the responsibility of Paul of Tarsus as part of the trend among first century Christians of distancing themselves from their theological cousins reversed or altered several common practices. For instance, in the mid-first century catechismal document The Teaching of the Twelve Apostles to the Heathen, commonly called the Didache, the author instructs believers to fast on Wednesdays and Fridays rather than on Mondays and Thursdays as the “hypocrites” did.
Among the Jews, Samaritans, and other Hebrew groups in the first century CE, men went about outside covered and women uncovered, and during religious services prayed that way. In his first letter to the Corinthians (14:4-13), Paul turned this on its head, prescribing rather that men should be uncovered and women covered, largely to mirror Gentile rather than Jewish practice. Moreover, Paul prescribing veiling not just for high-born but for all women.
The verses in the Quran which deal with some of Muhammad’s followers complaining that his wives are unveiled point out that the Prophet himself felt it unnecessary to ask them to do so and did that only because of the weakness of those same followers. Ask yourself this: was Muhammad in error, or were those self-righteous followers?
Aisha bint Tahla, granddaughter of Muhammad’s father-in-law Abu Bakr, is famous for declaring, when similar followers of Muhammad suggested she veil that, “Since the almighty hath put on me the stamp of beauty, it is my wish that the public should view the beauty and thereby recognize His grace unto them. On no account, therefore, will I veil myself.”
When the Abbasids of Khorasan in the northwest of Iran succeeded to the Caliphate, they instituted a number of reforms that included instituting Iranian administration in what was by then a far-flung empire. They also mandated for all Muslims the then Iranian-only practice of prescribed veiling for women, adopting from the Roman Empire the practice of spreading out the practice to all social classes.