The heresy of Peor is an event related in the Torah at Numbers 25:1–15. Back references to the event occur in Numbers 25:18 and 31:16, Deuteronomy 4:3, Joshua 22:17, Hosea 9:10; Psalm 106:28. Another reference is found in the New Testament, 1 Corinthians 10:8.
The story proceeds from that of the prophet Balaam, in which he ascends the mountain of Pe‘or, and makes sacrifices to God from atop it. Having finished his sacrifices, Balaam views the Israelites on the plain below, and although hired to curse them, pronounces a blessing over them, prophesying their blessed nature and destruction of Moab. When the narrative focus returns to the point of view of the Israelites, the contrast between Balaam's voiced opinion of them, and their actual behaviour, is distinctly noticeable.
According to the Torah, the Israelites, after spending a short time in the plain of Moab, begin to involve themselves with the Moabite women. Consequently, under the influence of Moabite culture, the Israelites begin whoring after the Moabite gods, and join themselves to Baal Peor (Hebrew בעל פעור Ba‘al Pə‘ôr), in the Septuagint Beelphegôr, a baal associated with Mount Pe‘or.