Study Guide Yevamot 43 Rabbi Avahu said that whenever there is a Mishna with an unattributed opinion and the same topic has a debate in a braita, we hold by the Mishna. A difficulty is raised against this from an unattributed opinion in a Mishna in Kelim 13:8 and it is a source of debate in a braita and yet, we do not hold like the Mishna. Rabbi Avahu answered that this Mishna was an exception to the rule as Rabbi Yochanan and Reish Lakish both held that the Mishna itself was inaccurate. What about the Mishna was inaccurate? The Gemara suggests a number of possibilities until it found an answer that worked – that the Mishna actually ended with the words “this is Rabbi Shimon’s opinion” and therefore was not an unattributed Mishna. There are varying opinions regarding exactly how long the waiting period is for a woman to get betrothed? Does one need three full months or can it be two and a half? If three full months are needed, is the day of death/day of the bethrothal included in the count? Rabbi Yosi said in the Mishna that a widow cannot get engaged immediately because she needs to mourn. A difficulty is raised from laws of Tisha B’av and the days leading up to it as laws of mourning are in effect and yet one can get betrothed. A number of solutions are suggested, some of which emend the text of the Mishna. However, questions are raised against the second emendation of the text. And ultimately all the answers brought are rejected and the difficulty from Tisha B’av is answered by saying there is a tannaitic debate and each source holds by a different opinion. Rav Ashi raises a question on this answer as well and responds by distinguishing between mourning on Tisha B’av and mourning for a dead relative as they are not the same type of mourning.