Study Guide Yevamot 21 Presentation in PDF format Today's daf is sponsored by Rabbi Dan Ross and Rabbi Jade Sank Ross in honor of the birth of their daughter Adina Sydney Ross, Adina Sapir bat Harav Daniel Zalman v'harabah Yofi Channah. "May the joy of your arrival on Erev Purim follow you throughout your life, may you live to see your world fulfilled, may your destiny be for worlds still to come, and may you trust in generations past and yet to be." If a high priest performs yibum with a widow, is the yibum effective to exempt a second wife? This is a debate between Rabbi Yochanan and Rabbi Elazar. A difficulty is raised against one of the opinions. From where can we find a hint in the Torah for the rabbinic extension of the prohibitions for forbidden relationships to other relatives? Four different verses are brought. A braita is brought which lists eight relatives that are included in the rabbinic decree. One of them mentioned is by Torah law – if so, why does it appear here? Rav says there are four relatives that are forbidden only that generation but it is not extended to earlier or later generations. What are the four cases? Also, one’s daughter-in-law is forbidden by Torah law. Therefore, it is assumed that it is referring to one’s daughter’s daughter-in-law, who is forbidden on account of one’s son’s daughter-in-law. Is the wife of one’s maternal half-uncle through their mother (the uncle and her mother have the same mother) forbidden?  Why is this not considered a decree on a decree? To answer the question they bring a statement of Rav Yehuda bar Shila that any familial relationship where a woman is forbidden, if it is a man, his wife is forbidden as well. Since there are a number of exceptions to that rule that Rava states, the assumption is that he is referring to the case at hand. What is the difference between his case and the exceptions? What about the wife of one’s paternal great uncle or one’s paternal great aunt through his grandfather?