It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that Sayyiduna Isra'il (Ya'qub, peace be upon him) was afflicted with sciatica ('irq al-nasa), because of which he would moan in pain through the nights. He vowed that if Allah cured him, he would not eat meat that had veins in it. So the Jews also declared it forbidden (for themselves), and then this verse was revealed: "All food was lawful to the Children of Israel except what Isra'il had made unlawful for himself before the Torah was revealed. Say: Bring the Torah and recite it, if you are truthful." [Surah Al Imran: 93] Indeed, this event took place before the revelation of the Torah. This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), and they did not record it.