וַיִּקְח֖וּ אֶת־כְּתֹ֣נֶת יוֹסֵ֑ף וַֽיִּשְׁחֲטוּ֙ שְׂעִ֣יר עִזִּ֔ים וַיִּטְבְּל֥וּ אֶת־הַכֻּתֹּ֖נֶת בַּדָּֽם׃
And they took Joseph’s coat, and killed a he-goat, and dipped the coat in the blood;
Read kabbalistic (mystical) interpretation of Genesis 37:31: and classical mystical sources.