Aaron spake all the words - It is likely that Aaron was better acquainted with the Hebrew tongue than his brother, and on this account he became the spokesman. See Clarke on Exodus 4:14 (note).

Did the signs - Turned the rod into a serpent, made the hand leprous, and changed the water into blood. See Clarke on Exodus 4:6 (note) and Exodus 4:8 (note).

And Aaron spake all the words which the Lord had spoken unto Moses,.... As Moses had related to him, being his mouth and spokesman:

and did the signs in the sight of the people; not Aaron, but Moses, and these were the turning of his rod into a serpent, and the serpent into a rod again; putting his hand into and out of his bosom, when it was leprous, and then doing the same when it was well again; and taking water out of the river, and changing it into blood, which he did for the confirmation of his mission.

And Aaron spake all the words which the LORD had spoken unto Moses, and did the signs in the sight of the people.

4:24-31 God met Moses in anger. The Lord threatened him with death or sent sickness upon him, as the punishment of his having neglected to circumcise his son. When God discovers to us what is amiss in our lives, we must give all diligence to amend it speedily. This is the voice of every rod; it calls us to return to Him that smites us. God sent Aaron to meet Moses. The more they saw of God's bringing them together, the more pleasant their interview was. The elders of Israel met them in faith, and were ready to obey them. It often happens, that less difficulty is found than was expected, in such undertakings as are according to the will of God, and for his glory. Let us but arise and try at our proper work, the Lord will be with us and prosper us. If Israel welcomed the tidings of their deliverance, and worshipped the Lord, how should we welcome the glad tidings of redemption, embrace it in faith, and adore the Redeemer!