Commentary for Yoma 7:5
כֹּהֵן גָּדוֹל מְשַׁמֵּשׁ בִּשְׁמֹנָה כֵלִים. וְהַהֶדְיוֹט בְּאַרְבָּעָה, בְּכֻתֹּנֶת וּמִכְנָסַיִם וּמִצְנֶפֶת וְאַבְנֵט. מוֹסִיף עָלָיו כֹּהֵן גָּדוֹל, חשֶׁן וְאֵפוֹד וּמְעִיל וָצִיץ. בְּאֵלּוּ נִשְׁאָלִין בְּאוּרִים וְתֻמִּים. וְאֵין נִשְׁאָלִין אֶלָּא לַמֶּלֶךְ וּלְבֵית דִּין וּלְמִי שֶׁהַצִּבּוּר צָרִיךְ בּוֹ:
The high-priest officiates in eight vestments and a regular priest in four: coat, breeches, turban, and girdle. The high-priest, in addition, wears four: choshen [breastplate], ephod, robe, and tzitz (head-plate). In these, inquiries are made of the urim vethumim [i.e., the high-priest must be wearing the eight garments when he makes inquiries of the urim vethumim. How are inquiries made? The face of the inquirer is behind the priest who is inquired of. His (the latter's) face is towards the ark. The inquirer asks: "Shall I do this thing or not?" He does not ask in a loud voice and not in his heart, but in a low voice; and the holy spirit invests the priest and he looks at the choshen. He sees letters projecting from the choshen before his face — "Do this," or "Do not do this." For on the stones of the choshen were written the names of the twelve tribes, and Avraham, Yitzchak, and Yaakov, and "shivtei Kah" ("the tribes of the L rd"), so that the entire alphabet was represented. And the holy spirit informed the priest how to combine the projecting letters so that the meaning was apparent.] And inquiries are made only for the king, for the beth-din, and for the one acting on behalf of the congregation, [it being written (Numbers 27:21): "And before Elazar the priest shall he stand" — the king; "and all the children of Israel with him" — the one whom all the children of Israel are with, to go out to war after him — the priest anointed for war, the one needed by the congregation; "and the entire congregation" — the Great Sanhedrin.]
Bartenura on Mishnah Yoma
English Explanation of Mishnah Yoma
The high priest adds the breastpiece, the ephod, the robe and the frontlet.
In these were the Urim and Tummim inquired of. But they were not inquired of except by the king, by the head of the court or by one whom the community needs.
This mishnah completes the first seven chapters of Yoma, all of which dealt with the Temple Yom Kippur ritual.
Sections one and two: The first two sections of the mishnah outline the difference between the clothes that the high priest wore on normal occasions throughout the year (not on Yom Kippur), and the clothes that a normal priest wore. The high priest has eight pieces of clothing (see above 3:4) whereas the normal priest has only four pieces. These are all discussed in Exodus 28
Section three: The Urim and Tummim, the oracular stones used in the First Temple, are only asked questions when the high priest is wearing his eight pieces of clothing. And not anyone can ask a question of the Urim and Tummim. Only the king, the head of the court or other high officials of the community may ask questions. For more information about the Urim and Tummim, how they are understood by modern biblical scholars and how they are understood in the aggadah, I suggest consulting the Encyclopedia Judaica.