Midrasch zu Jechezkiel 1:7

The Chajjôth stand next to the throne of His glory and they do not know the place of His glory. The Chajjôth stand in awe and dread, in fear and trembling, and from the perspiration of their faces a river of fire arises and goes forth before Him, as it is said, "A fiery stream issued and came forth from before him…"(Dan. 7:10). And the wings of Gallizur the angel, who stands next to the Chajjôth, (are spread forth) so that the fire which consumes the fire of the angels should not burn (them). Two Seraphim stand, one on His right and one on His left, each one has six wings, with twain they cover their face so as not to behold the presence of the Shekhinah, with twain they cover their feet so that they should not be seen before the presence of the Shekhinah, || so that the standing of the foot of the calf might be forgotten. With twain do they fly, praising and reverencing, and they sanctify. One answers and another calls, one calls and another answers, and they say, "Holy, Holy, Holy, is the Lord of Hosts; the whole earth is full of his glory" (Isa. 6:3).

(Lev. 22:27) “When a bull or a sheep or a goat.” 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) […].”⁴³Lev. R. 27:3; PRK 9:3. It is also written (in Is. 6:2), “Above Him stood the seraphim, six wings to each one… 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.”⁴⁴Cf. Hag. 13b. [This is] because (according to Ezek. 29:16), “And it shall no more be a source of satisfaction against the House of Israel to recall iniquity.”⁴⁵In other words, the seraphim covered their calf feet, lest they recall the sin of the golden calf. (Is 6:2:) “And with two he flew,” for praise. We are taught there (in RH 3:2), “All the shofars are valid except that of a cow, since it is from a calf; for (according to Ezek. 29:16), “And it shall no more be a source of satisfaction against the House of Israel to recall iniquity.” We have been taught there⁴⁶See Sanh. 7:4. (in Lev. 20:16): “You shall kill the woman and the beast.” If a woman sins, what is the beast’s sin? It is simply because a stumbling block came to the woman on account of [the beast]. Therefore the Scripture said, “So that the beast will not pass through the market, where they will say, ‘This is the beast on account of which such and such a woman was killed.’” [This is] because (according to Ezek. 29:16), “And it shall no more be a source of satisfaction against the House of Israel to recall iniquity.” Now we have been taught: For what reason did they say, “A suspected adulteress (sotah) is not to drink from the cup of her colleague (i.e., another suspected adulteress)?”⁴⁷According to Sot. 2:2, a new earthenware dish was to be used for each such trial by ordeal. [It is] so that the people will not say, “When such and such a woman drank of this cup, she died.” [This is] because (according to Ezek. 29:16), “And it shall no more be a source of satisfaction against the House of Israel to recall iniquity.” So also here (in Lev. 22:27), “When a bull or a sheep or a goat is born.” Is a bull born? Is not a calf born? It is simply because of what is written (in Exod. 32:8), “they have made themselves a golden calf.” Hence the Scripture called it a “bull”, and did not call it a "calf.”

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.