מסכת יומא עג:ב:
למה נקרא שמן אורים ותומים
אורים שמאירין את דבריהן
תומים שמשלימין את דבריהן
Tractate Yoma 73:b:
Why is it called Urim VeTummim? Urim, which is based on the word or, light, is so called because it illuminates and explains its words. Tummim,which is based on the word tam, completed, is because it fulfills its words,which always come true.
יומא עג:ב:
ואף על פי שגזירת נביא חוזרת גזירת אורים ותומים אינה חוזרת שנאמר (במדבר כז, כא) במשפט האורים.
Yoma 73:b:
The Gemara notes the reliability of the Urim VeTummim: Even though a decree of a prophet can be retracted, as sometimes a dire prophecy is stated as a warning and does not come true, a decree of the Urim VeTummim cannot be retracted. As it is stated: “By the judgment of the Urim” (Numbers 27:21).
בניהו בן יהוידע זה סנהדרין ואביתר אלו אורים ותומים וכן הוא אומר ובניהו בן יהוידע על הכרתי ועל הפלתי ולמה נקרא שמם כרתי ופלתי כרתי שכורתים דבריהם פלתי שמופלאים בדבריהם...
Benayahu ben Yehoyada corresponds to the Sanhedrin, since he was the head of the Sanhedrin, and Evyatar corresponds to the Urim VeTummim, as Evyatar ben Ahimelekh the priest would oversee inquiries directed to the Urim VeTummim (see I Samuel 23:9). And so it says regarding Benayahu ben Yehoyada’s position as head of the Sanhedrin: “And Benayahu ben Yehoyada was over the Kereti and over the Peleti” (II Samuel 20:23). And why was the Sanhedrin called Kereti UPeleti? It was called Kereti because they were decisive [koretim] in their pronouncements. It was called Peleti because their pronouncements and wisdom were wondrous [mufla’im]. The head of the Kereti UPeleti was the head of the Sanhedrin. According to the order of the verse, upon being instructed by King David to go to war, the Sages first consulted with Ahitophel, then with the Sanhedrin, then they would ask the Urim VeTummim, and only thereafter was the general of the king’s army, Yoav, given the command to ready the military for battle.
תא שמע (במדבר כו, נו) בין רב למעט ועוד תניא עתידה ארץ ישראל שתתחלק לשלשה עשר שבטים שבתחלה לא נתחלקה אלא לשנים עשר שבטים ולא נתחלקה אלא בכסף שנאמר בין רב למעט אמר רבי יהודה סאה ביהודה שוה חמש סאין בגליל
ולא נתחלקה אלא בגורל שנאמר (במדבר כו, נה) אך בגורל ולא נתחלקה אלא באורים ותומים שנאמר על פי הגורל הא כיצד אלעזר מלובש אורים ותומים ויהושע וכל ישראל עומדים לפניו וקלפי של שבטים וקלפי של תחומין מונחין לפניו
והיה מכוין ברוח הקדש ואומר זבולן עולה תחום עכו עולה עמו טרף בקלפי של שבטים ועלה בידו זבולן טרף בקלפי של תחומין ועלה בידו תחום עכו וחוזר ומכוין ברוח הקדש ואומר נפתלי עולה ותחום גינוסר עולה עמו טרף בקלפי של שבטים ועלה בידו נפתלי טרף בקלפי של תחומין ועלה בידו תחום גינוסר וכן כל שבט ושבט
The Gemara suggests: Come and hear a proof. The verse states: “According to the lot shall their inheritance be divided between the more and the fewer” (Numbers 26:56). Evidently, whether the tribe had many or few people, the tribe as a whole received a portion equal to that of every other tribe, and each individual within the tribe received a different amount of land than those in other tribes. And another proof can be seen from that which is taught in a baraita: Eretz Yisrael is destined to be divided among thirteen tribes during the messianic era, unlike the division in the time of Joshua. As, initially the land was divided only among twelve tribes, as the Torah does not allot a portion to the tribe of Levi. The baraita continues: And the land was divided only with money, such that each tribe that received a portion more valuable than average compensated another tribe that had received a portion less valuable than average, as it is stated: “Between the more and the fewer.” Rabbi Yehuda said: The area of land whose yield is a se’a of grain in Judea is so valuable that it is equal in value to the area necessary to produce five se’a of grain in the Galilee. The baraita continues: And the land was divided only by a lottery, as it is stated: “Only by lot shall the land be divided” (Numbers 26:55). And the land was divided only with the Urim VeTummim, as it is stated: “By the pronouncement of the lot” (Numbers 26:56). The baraita asks: How can these texts be reconciled? One indicates that the land was divided by lottery and the other indicates that the land was divided with the Urim VeTummim. The baraita explains: Elazar the High Priest was dressed with the Urim VeTummim, and Joshua and all the Jewish people were standing before him, and a lottery receptacle containing the names of the tribes and another lottery receptacle containing the names of the boundaries of the twelve different regions of Eretz Yisrael were placed before him. And Elazar would ascertain the assignments of land with the Divine Spirit and say, in accordance with the notification of the Urim VeTummim: The name of the tribe Zebulun now emerges from the receptacle in the lottery, and the region whose boundary is Akko emerges with it from the other receptacle. After stating this, he would mix the lots in the receptacle of the tribes and the lot of Zebulun would emerge in his hand. He would then mix the lots in the receptacle of the boundaries, and the boundary of Akko would emerge in his hand. And Elazar would repeat the process and ascertain the assignments with the Divine Spirit and say: The name of the tribe Naftali now emerges, and the region whose boundary is Ginnosar emerges with it from the other receptacle. After stating this, he would mix the lots in the receptacle of the tribes and the lot of Naftali would emerge in his hand. He would then mix the lots in the receptacle of the boundaries, and the boundary of Ginnosar would emerge in his hand. And so he would proceed for each and every tribe.
רשי:
ודילמא - הא דקא מדכר קרא בסנהדרי גדולה משום שאילת אורים ותומים הוא אתא לאשמעינן דנשאלין לסנהדרין באורים ותומים וכן למלך וכן למשוח מלחמה אבל לא להדיוט ולעולם לענין לצאת למלחמה יוצאין בלא רשות סנהדרי:
שבועות טז:א
עליונה שלא היתה קדושתה גמורה עמי הארץ היו נכנסין שם ואוכלין שם קדשים קלים אבל לא מעשר שני וחברים אין אוכלין שם לא קדשים קלים ולא מעשר שני ומפני מה לא קידשוה
שאין מוסיפין על העיר ועל העזרות אלא במלך ונביא ואורים ותומים ובסנהדרין של ע"א ובשתי תודות ובשיר
Tractate Shevuot 16:a:
The baraita continues: With regard to the lower pond, whose consecration was complete, amei ha’aretz, uneducated people who were not scrupulous in their observance of the mitzvot relating to tithes and to ritual purity, would enter into there and would partake of offerings of lesser sanctity that may be eaten in all of Jerusalem there, but they would notpartake of second tithe there because they conducted themselves stringently concerning this matter. And ḥaverim,who were meticulous in their observance of those mitzvot, would partake of both offerings of lesser sanctity and second tithe there.