C. F. Keil and Franz Delitzsch on Numbers 11:27-28

Num 11:27-28

This phenomenon in the camp itself produced such excitement, that a boy (הנּער, with the article like הפּליט in Gen 14:13) reported the thing to Moses, whereupon Joshua requested Moses to prohibit the two from prophesying. Joshua felt himself warranted in doing this, because he had been Moses’ servant from his youth up (see at Exo 17:9), and in this capacity he regarded the prophesying of these men in the camp as detracting from the authority of his lord, since they had not received this gift from Moses, at least not through his mediation. Joshua was jealous for the honour of Moses, just as the disciples of Jesus, in Mar 9:38-39, were for the honour of their Lord; and he was reproved by Moses, as the latter afterwards were by Christ.