A.T. Robertson Commentary Acts 7:40

"saying unto Aaron, Make us gods that shall go before us: for as for this Moses, who led us forth out of the land of Egypt, we know not what is become of him." — Acts 7:40 (ASV)

Gods which shall go before us (θεους ο προπορευσοντα ημων). Exodus 32:1. As guides and protectors, perhaps with some allusion to the pillar of fire and of cloud that had gone before them (Exodus 13:21). The future indicative here with ο (relative) expresses purpose.

Ye wot not (ουκ οιδαμεν). We do not know. How quickly they had forgotten both God and Moses while Moses was absent in the mount with God.

Become of him (εγενετο αυτω). Happened to him. "This" (ουτος) here is a contemptuous allusion to Moses by the people.