Exodus 4:16
And he shall be thy spokesman unto the people: and he shall be, even he shall be to thee instead of a mouth, and thou shalt be to him instead of God.
Cross-references
In Exodus 4:28, Moses tells Aaron God's words and shows signs, immediately following the role assignment in v16.
In Exodus 4:30, Aaron speaks the words from Moses, directly acting as his mouth as commanded in v16.
Exodus 7:1 reiterates the roles: Moses as God to Pharaoh, Aaron as prophet—confirming the same relationship from 4:16.
Exodus 7:2 shows the commission in action: Moses speaks God's words, Aaron delivers them—fulfilling the roles from 4:16.
In Jeremiah 1:9, God puts His words in Jeremiah's mouth, echoing the divinely appointed mouthpiece role given to Aaron in Exodus 4:16.
Psalm 82:6 calls human judges 'gods'—echoing the concept of Moses being 'as God' to Aaron, a representative divine role.
In Job 36:2, Elihu claims to speak on God's behalf, similar to Aaron speaking for Moses who represents God in Exodus 4:16.