וַיֹּ֨אמֶר יְהוָ֜ה אֶל־מֹשֶׁ֗ה קַ֚ח אֶת־כָּל־רָאשֵׁ֣י הָעָ֔ם וְהוֹקַ֥ע אוֹתָ֛ם לַיהוָ֖ה נֶ֣גֶד הַשָּׁ֑מֶשׁ וְיָשֹׁ֛ב חֲר֥וֹן אַף־יְהוָ֖ה מִיִּשְׂרָאֵֽל׃
And the LORD said unto Moses: ‘Take all the chiefs of the people, and hang them up unto the LORD in face of the sun, that the fierce anger of the LORD may turn away from Israel.’
Read kabbalistic (mystical) interpretation of Numbers 25:4: and classical mystical sources.