Pensée juive sur Les Nombres 11:27

This explains what is stated further in the parshah (Numbers 11:27-28): "And the youth ran and told Moses, saying: 'Eldad and Medad are prophesying within the camp. And Joshua the son of Nun, the servant of Moses from his youth, answered and said: 'My lord, Moses, imprison them!'" The words of Joshua certainly require explanation. What is their offense and what is their sin in prophesying, that he should ask Moses to imprison them because of this? According to what we have written, however, it is clear. Joshua saw these two as militating against the divine intent of having all of them derive nourishment from the spirit of Moses to the end of universal accord and consent. These two were making a head of themselves and desiring to prophesy by a distinct spirit. And though the spirit of the L-rd in their mouth was true, their prophesying to Israel in a distinct style was liable to result in disorganization and ineffective leadership. For this reason Joshua asked that they be placed into prison, where they could prophesy for themselves.