Midrash su Levitico 8:8

7) (Vayikra 8:8) "And he placed the choshen upon him.": This section was learned for its time and for future generations (for the donning of the priestly vestments) for the daily service and for the Yom Kippur service. (It is just that) every day he serves in the golden vestments, and on Yom Kippur, in the white (linen) vestments.

R. Jacob bar Zavday in the name of R. Abbahu opened < his discourse > (with Ezek. 29:16): AND IT SHALL NO MORE BE A SOURCE OF SATISFACTION AGAINST THE HOUSE OF ISRAEL TO RECALL INIQUITY (i.e., the iniquity of the golden calf).⁵²Tanh., Lev. 8:8; Lev. R. 27:3; PRK 9:3. It is also written (in Is. 6:2): ABOVE HIM STOOD THE SERAPHIM….WITH TWO HE COVERED HIS FACE, so as not to look at the Divine Presence, WITH TWO HE COVERED HIS FEET, so that the face of the Divine Presence would not see them, since it is written (in Ezek. 1:7): AND THE SOLE OF THEIR FEET WAS LIKE THE SOLE OF A CALF'S FOOT.⁵³Cf. Hag. 13b. Thus (according to Ezek. 29:16): AND IT SHALL NO MORE BE A SOURCE OF SATISFACTION AGAINST THE HOUSE OF ISRAEL TO RECALL INIQUITY.⁵⁴In other words, the seraphim covered their calf feet, lest they recall the sin of the golden calf.