Background
R. Isaac son of Rab Judah (or Isaac b Judah or YIẒḤAḲ BAR JUDAH, or Yitzchaq bar Judah. Hebrew: רב יצחק בריה דרב יהודה) was a fourth generation Amora sage of Babylon. His father was Judah ben Ezekiel who was his Teacher par excellence, and he debated many Halakhaic issues with him.
His father regarded him highly, and would submit statements in his son"s name, which was considered unusual, since usually an Amora does not submit statements in the name of their students (but rather, the other way around).
Career
Foreign a Rishon sage, with a similar name, see: Isaac ben Judah ibn Ghayyat (1030, Spain). Foreign the Portuguese Jewish leader during The expulsion of Jews from Spain, see: Isaac ben Judah Abrabanel (Lisbon, 1437, also known as The Abarbanel). Foreign the Tosafist sage, see: Judah b.
Isaac of Paris (1166, also known as Judah Messer Leon).
At times he would commentate on his father"s work. Rab Isaac was born to Rabbi Judah probably at an old age.
In his childhood already he was showing signs of wisdom and his wit was more than the rest of his peers. He did not marry until a very late age, because his father did not know where to find a family with no Marriage restrictions, until Ulla once came to visit his house and guided him with the signs needed to locate those with no Marriage restrictions.
After their death he became a student of Rami bar Hama, who was considered an Oker Harim scholar, and would reply to each question addressed to him with reason rather than one relying on a teaching (from the Baraitas) that had preceded him, contarary to Rav Sheshet who would reply based on previous sources.
This thinking of Rami bar Hama made Rab Isaac leave his lectures, and go study under Rav Sheshet. Rab Isaac developed a special method of testing Tzitzit of Tekhelet, whether they are painted the right material of a certain Gastropoda"s blood.
