וַיֹּ֣אמֶר מֹשֶׁ֔ה אֶל־שֹׁפְטֵ֖י יִשְׂרָאֵ֑ל הִרְגוּ֙ אִ֣ישׁ אֲנָשָׁ֔יו הַנִּצְמָדִ֖ים לְבַ֥עַל פְּעֽוֹר׃
And Moses said unto the judges of Israel: ‘Slay ye every one his men that have joined themselves unto the Baal of Peor.’
Read halakhic rulings (Jewish law) on Numbers 25:5: and classical halakhic sources.