That will be the proof that I have sent you.” But Moses replied, “When I go to the Israelites and say to them, ‘The God of your ancestors sent me to you,’ they will ask me, ‘What is his name?’
So what can I tell them?” God said, “I am who I am. You must tell them: ‘The one who is called I Am has sent me to you.’ Tell the Israelites that I, the Lord, the God of their ancestors, the God of Abraham, Isaac, and Jacob, have sent you to them.
The LORD said to Moses, Take you Joshua the son of Nun, a man in whom is the spirit, and lay your hand on him; Moses, after having been the leader of his people for forty years, is at length to get his discharge.
Nothing has yet been determined regarding a successor.
The point is, on every account, too important to be left open till the present leader has passed away.
A change of leadership, always hazardous, is especially hazardous when the army is in the field and the enemy is on the watch. If the Divine wisdom judged it necessary that Eleazar should be invested with the high priesthood before Aaron died, much more is it necessary that, before Moses lays down the scepter, a successor should be appointed and placed in command.