Joshua was well prepared to become Israel’s leader. He had already led Israel in battle (compare Exodus 17:8–16). He had also served as Moses’s assistant for many years (Numbers 11:28; compare Exodus 33:11).
Joshua was one of the two faithful spies who knew the people of Israel well (Numbers 13–14). The Spirit of God was with Joshua (compare 11:25–29). His close relationship with God gave him wisdom for the work ahead (for example, Deuteronomy 34:9).
lay your hands on him: This act symbolized transferring authority from an elder leader to his assistant (compare Numbers 8:10–14). Moses did this publicly so that no one would question Joshua's leadership.