Numbers 27:15

“And Moses spake unto the Lord, etc.] Having requested to go into the land and see it, which was denied him; and perceiving he must quickly die, and being a man of a public spirit, and concerned for the welfare of the people of Israel, prays that a successor might be nominated and appointed: saying; as follows.”

“And Moses spake unto the Lord - Concerning his successor. We should concern ourselves both in our prayers and in our endeavours for the rising generation, that God's kingdom may be advanced among men, when we are in our graves. Numbers 27:16”

“27:15-17 Israel was on the threshold of a long battle for Canaan; Moses did not want them to flounder without a leader or lose their way like sheep without a shepherd (cp. 1 Kgs 22:17; Ezek 34:5; Matt 9:36).”

“Consecration of Joshua as the Successor of Moses. - Num 27:15-17. The announcement thus made to Moses led him to entreat the Lord to appoint a leader of His people, that the congregation might not be like a flock without a shepherd. As "God of the spirits of all flesh," i.e., as the giver of life and breath to all creatures (see at Num 16:22), he asks Jehovah to appoint a man over the congregation, who should go out and in before them, and should lead them out and in, i.e., preside over and direct them in all their affairs. ובוא צאת ("go out," and "go in") is a description of the conduct of men in every-day life ( Deu 28:6; Deu 31:2; Jos 14:11). והביא הוציא ("lead out," and "bring in")…”