In the Four Cups of Wine of Pesach Night: Pesachim 112a
This Mitzvah is potentially greater than the Biblical Mitzvah of Reciting Shema, in saying the Hallel-Prayer of Praise: Berachot 14a
Using Charity from the Communal Kitchen for publicizing miracles: Pesachim 112a
Forbidding fasting on Chanukah, because of its element of publicizing its miracles: Rosh HaShanah 18b