פירוש על עבודה זרה 15:5

Kalenda, from which the English word calendar derives, refers to the first day of the month, and especially to the first day of the year. Saturnalia was a popular Roman holiday on the 17th of December, dedicated to the god, Saturn. Kratesis, which was on the first of August, commemorated the day that Augustus conquered Alexandria in Egypt. Note that I have used the names of these holidays as Albeck states that they should be read. Medieval scribes often did not know what these holidays were or what their names were and different forms of the words can be found in other versions of the mishnah.
The anniversary of the accession of the king to the throne is also considered to be a day of celebration full of idolatrous practices.
The final two days of idolatrous celebration are personal: one’s birthday and the anniversary of the death of a close relative. On these days non-Jews would make idolatrous celebrations. Interestingly, Jews did not traditionally celebrate birthdays because it was seen to be a non-Jewish custom.

The opinion in the previous section was that of Rabbi Meir, who held that pagans commemorate the anniversaries of all deaths. The rabbis disagree with Rabbi Meir and hold that only deaths where the body and clothes were burned on a funeral pyre are celebrated by idolatrous acts. If the body was not burned on the pyre then the day is not accompanied by idolatry and it is therefore permitted to conduct business with the non-Jew three days before.

As was previously stated it is forbidden to conduct business with non-Jews during the three days before the personal holidays mentioned in section two. Here the mishnah lists pagan holidays that Jews can conduct business during the three days before and are only forbidden from doing so on the holiday itself. These include the day that the non-Jew shaves his beard and lock of hair, which refers to a lock of hair grown at the back of one’s head and is shaved once a year; the day of return from a long trip by sea; the day that one is released from prison and the day in which one marries off one’s son and makes him a celebratory feast.