Acts 7:40

Saying unto Aaron, Make us gods to go before us: for as for this Moses, which brought us out of the land of Egypt, we wot not what is become of him.

Cross-references

Exodus 32:1 is the exact source Stephen quotes — the people demand Aaron make gods because Moses delayed.

Deuteronomy 9:16 provides Moses' eyewitness account of the same golden calf sin Stephen references, confirming the idolatry.