See the marginal reference. The women who assembled at the entrance of the tent of meeting were most probably devout women who loved the public service of religion. The giving up of their mirrors for the use of the sanctuary was a fit sacrifice for such women to make (compare Exodus 35:22 note).
Related Commentaries of Exodus 38:8
Exodus 38:8
8 And he made the laver of brass, and the foot of it of brass, of the lookingglassesa of the women assembling, which assembled at the door of the tabernacle of the congregation.