וַיִּצָּ֥מֶד יִשְׂרָאֵ֖ל לְבַ֣עַל פְּע֑וֹר וַיִּֽחַר־אַ֥ף יְהוָ֖ה בְּיִשְׂרָאֵֽל׃
And Israel joined himself unto the Baal of Peor; and the anger of the LORD was kindled against Israel.
Read kabbalistic (mystical) interpretation of Numbers 25:3: and classical mystical sources.