And thou shalt take this rod in thine hand, wherewith thou shalt do signs.

Wesley's Notes

4:17 Take this rod - The staff or crook he carried as a shepherd, that he might not be ashamed of that mean condition out of which God called him. This rod must be his staff of authority, and must be to him instead, both of sword and sceptre.

Matthew Henry's Concise Commentary

4:10-17 Moses continued backward to the work God designed him for; there was much of cowardice, slothfulness, and unbelief in him. We must not judge of men by the readiness of their discourse. A great deal of wisdom and true worth may be with a slow tongue. God sometimes makes choice of those as his messengers, who have the least of the advantages of art or nature, that his grace in them may appear the more glorious. Christ's disciples were no orators, till the Holy Spirit made them such. God condescends to answer the excuse of Moses. Even self-diffidence, when it hinders us from duty, or clogs us in duty, is very displeasing to the Lord. But while we blame Moses for shrinking from this dangerous service, let us ask our own hearts if we are not neglecting duties more easy, and less perilous. The tongue of Aaron, with the head and heart of Moses, would make one completely fit for this errand. God promises, I will be with thy mouth, and with his mouth. Even Aaron, who could speak well, yet could not speak to purpose, unless God gave constant teaching and help; for without the constant aid of Divine grace, the best gifts will fail.