Exodus 2:16

Now the priest of Midian had seven daughters; and they came and drew water, and filled the troughs to water their father's flock. This man is called a priest, but the Midianites apparently had not retained the pure religion of Abraham, Exodus 4:25, although the tradition of the true God persisted, as the name Reuel shows. The seven daughters of this priest, as dwellers in the wilderness, performed the work which the unmarried daughters of the Arab tribes do to this day.