Reference for Sanhedrin 31:21

מיד יועצין באחיתופל ונמלכין בסנהדרין ושואלין באורים ותומים אמר רב יוסף מאי קרא

Whence do we deduce this? — Said R. Abbahu: Scripture states, And he shall stand before Eleazar the Priest [who shall inquire for him by the judgment of the Urim before the Lord. At his word shall they go out and at his word they shall come in, both he and all the children of Israel with him even all the Congregation].<span class="x" onmousemove="('comment',' Num. XXVII, 21-22. ');">³⁷</span> 'He', refers to the King;<span class="x" onmousemove="('comment',' Joshua, who had regal authority. ');">³⁸</span> 'And all the children of Israel with him,' to the Priest anointed for the conduct of war;<span class="x" onmousemove="('comment',' And whose call to war must be heeded by all Israelites. ');">³⁹</span> and, 'all the Congregation,' means the Sanhedrin.<span class="x" onmousemove="('comment',' V. p. 3, no. 4. ');">⁴⁰</span> But perhaps it is the Sanhedrin whom the Divine Law instructs to inquire of the Urim and Tummim?<span class="x" onmousemove="('comment',' I.e., that none but the Sanhedrin (also the King and the Priest anointed for war) may enquire of the Urim and Tummim: but not because of any need to obtain their permission for the proclamation of war. ');">⁴¹</span> — But [it may be deduced] from the story related by R. Aha b. Bizna in the name of R. Simeon the Pious: A harp hung over David's bed, and as soon as midnight arrived, a northerly wind blew upon its strings and caused it to play of its own accord. Immediately David arose and studied the Torah until the break of dawn. At the coming of dawn, the Sages of Israel entered into his presence and said unto him: 'Our Sovereign King, thy people Israel need sustenance.' 'Go and support yourselves by mutual trading,'<span class="x" onmousemove="('comment',' Lit., 'one from another'. ');">⁴²</span> David replied, 'But,' said they, 'a handful does not satisfy the lion, nor can a pit be filled with its own clods.'<span class="x" onmousemove="('comment',' A community cannot live on its own resources. ');">⁴³</span> Whereupon David said to them: 'Go and stretch forth your hands with a troop [of soldiers].'<span class="x" onmousemove="('comment',' Invade foreign territory. ');">⁴⁴</span> Immediately they held counsel with Ahitophel and took advice from the Sanhedrin<span class="x" onmousemove="('comment',' Hence the ruling in the Mishnah, that the permission of the Sanhedrin was required for the proclamation of war. ');">⁴⁵</span> and inquired of the Urim and Tummim. R. Joseph said: What passage [states this]?

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