en_tn/act/07/31.md

he marveled at the sight

Moses was surprised that the bush was not burning up in the fire. This was previously known by Stephen's audience. AT: "because the bush was not burning up" (See: rc://en/ta/man/translate/figs-explicit)

as he approached to look at it ... Moses trembled and did not dare to look

This may mean Moses initially drew close to the bush to investigate, but then drew back in fear when he heard the voice.