Sifrei Bamidbar 96

(Bamidbar 11:27) "And the youth ran and he told Moses": Some say that this is Joshua, as in (Shemot 33:11) "And his (Moses') attendant, Joshua the son of Nun, a youth." R. Shimon says: It is written (Bamidbar, Ibid. 28) "And Joshua the son of Nun the servant of Moses from his youth responded": The first one, then, (i.e., "the youth") is not Joshua. (Ibid.) "My lord, Moses, kela'em": He said: My master, end them from the world, men who utter this evil report (that Moses will die). Rebbi says: (He said) Confine them in chains and collars, as in (Jeremiah 37:18) "… that you have put me into the prison house" ("beth hakeleh"). (Ibid. 29) "And Moses said to him: Are you zealous for my sake?" He said to him: Joshua, am I zealous for your sake? Would that you were a prophet like me (i.e., that your prophecy be directly from the L-rd), and that all of Israel be like you (in that regard) — (Ibid.) "Would that all the L-rd's people were prophets (by direct inspiration, and not by [indirect] "increase of spirit," viz. Ibid. 25). (Ibid. 30) "And Moses retired into (his tent in) the camp, he and the elders of Israel." We are hereby taught that He did not bring the calamity upon them until there entered (his tent) all of the righteous in the camp.