Said the king to him: 'I gave you the entire orchard to watch, handing to you all the fruits resulting from your care of it, and now you say: "Bring me additional men to help me watch!" I will bring others to help you watch. You must realize, however, that I will not pay them wages for watching from my own funds but that they will receive their wages from the payment that I have been giving to you!'
A similar answer was given by the Holy One, blessed be He, to Moses. When he told him 'I am not able to bear . . . alone, [Num. XI, 14f.] the Holy One, blessed be He, said to him: 'I gave you spirit and intelligence to govern My children. I sought no other, so that you might be unique in the enjoyment of that greatness. Yet you ask for the assistance of others! I want you to realize that they will receive nothing of Mine, but that I will take of the spirit which is upon thee (Num. XI, 17).
This notwithstanding, Moses lost nothing, for at the end of forty years He said to him: Take thee Joshua the son of Nun . . . And thou shalt put of thy honour upon him (ib. XXVII, 18 ff.). What is written of him? And Joshua the son of Nun was full of the spirit of wisdom; for Moses had laid his hands upon him (Deut. XXXIV, 9).
The Holy One, blessed be He, said: 'In this world only a few individuals have prophesied, but in the World to Come all Israel will be made prophets'; as it says, And it shall come to pass afterward, that I will pour out My spirit upon all flesh; and your sons and your daughters shall prophesy, your old men, etc.
(Joel III, 1).
Such is the exposition given by R. Tanhuma, son of R. Abba."
Midrash Rabbah XV. 25