The people will stone us: Stoning was a capital punishment where people threw rocks at the offender until he or she died. Stoning was the punishment for:
blasphemy (speaking against God; Leviticus 24:14–15).=,
idolatry (worshiping false gods; Leviticus 20:2; Deuteronomy 13:10), and
other acts of opposition against God.
The people might have considered rejecting a true prophet as blasphemy, which deserved the penalty of stoning.