Philo Judaeus De Migratione Abrahami 98

[98] and, moreover, carrying their zeal to a still higher degree, they likewise consecrated even their mirrors, that a laver might be made of them," ¹ in order that those who were about to assist at the sacrifices, washing their hands and their feet, that is to say, those works about which the mind is occupied and on which it is fixed, may have a view of themselves in a mirror according to the recollection of those mirrors of which the laver was made; for in this way they will never permit anything disgraceful to remain in any portion of the soul. And now they will dedicate the offering of fasting and patience, the most beautiful and sacred, and perfect of offerings.