Tosefta for Chagigah 35:11

[If] Shavuot fell on a Monday or on a Thursday or on a Friday or on a Sunday, [or] on any day of the week, Beit Shammai say, the "day of slaughter" is the next day. Beit Hillel say, there is no "day of slaughter" [rather, sacrifices are brought on Shavuot itself]. It so happened that Alexander (alt., "Alexa") died in Lod and the people of all the surrounding towns came to eulogize him. Rabbi Tarfon said to them, "Leave at once! We do not eulogize on a Festival!"