Musar על שבת 50:4

The next stage of comparison between the building of the Tabernacle and the creation of the universe as mentioned in the Midrash, and quoted by Rabbi Bachyah (page 661) was the comparison of G–d's directive: "Let all the waters be gathered to one place," to the instruction of making a copper basin from the waters of which the priests would wash their hands. This stage is one that involves the body rather than the soul which is involved in Torah study. The aspect of physical Sabbath observance by the body which is closest to the observance by the soul, is the preparation for the Sabbath such as bathing the body. Scripture discusses the washing away by G–d of the filth of the daughters of Zion, (Isaiah 4,4). This is presumably the source used by Rabbi Yehudah bar llai-i, who bathed himself and dressed in sheets every Sabbath Eve, and who, when dressed for the Sabbath, evoked the feeling in those who looked at him that they were seeing an angel of the Lord (Shabbat 25). The mystical dimension of the "sheets" no doubt was that he used something akin to the coverings of the Tabernacle, the יריעות. There is an interesting Mishnah in Demai 4,1 that, if someone who is not trusted to have tithed his produce before selling it has sold some produce to a customer and the customer forgot to tithe it before the Sabbath, this customer may accept the assurance of the seller that it was tithed prior to the sale if such an assurance is given on the Sabbath. The reason given for the ruling is that the seller experiences the holiness of the Sabbath and is afraid to desecrate it.