יְהִי־דָן֙ נָחָ֣שׁ עֲלֵי־דֶ֔רֶךְ שְׁפִיפֹ֖ן עֲלֵי־אֹ֑רַח הַנֹּשֵׁךְ֙ עִקְּבֵי־ס֔וּס וַיִּפֹּ֥ל רֹכְב֖וֹ אָחֽוֹר׃
Dan shall be a serpent in the way, A horned snake in the path, That biteth the horse’s heels, So that his rider falleth backward.
Read halakhic rulings (Jewish law) on Genesis 49:17: and classical halakhic sources.