Reference for Rosh Hashanah 49:11
ואותו היום מתה אמו של בן זזא והספידה ר"ג הספד גדול לא מפני שראויה לכך אלא כדי שידעו העם שלא קידשו ב"ד את החדש:
Our Rabbis taught: Once the heavens were covered with clouds and the likeness of the moon was seen on the twenty-ninth of the month. The public were minded to declare New Moon, and the Beth din wanted to sanctify it, but Rabban Gamaliel said to them: I have it on the authority of the house of my father's father tha the renewal of the moon takes place after not less than twenty-nine days and a half and two-thirds of an hour and seventy-three halakin.<span class="x" onmousemove="('comment',' Lit., 'parts' (sc. of one hour) , 73/1080 X 60 m == 4 m 3 1/3 sec. The new moon, therefore, could not be seen on the twenty-ninth day.');"><sup>24</sup></span> On that day the mother of Ben Zaza died, and Rabban Gamaliel made a great funeral oration over her, not because she had merited it, but so that the public should know that the Beth din had not sanctified the month.<span class="x" onmousemove="('comment',' As a funeral oration would not be delivered on New Moon, which was regarded as a holy day.');"><sup>25</sup></span>