Rashi on Leviticus 23:24/רש"י על ויקרא כ״ג:כ״ד

1זכרון תרועה [THERE SHALL BE UNTO YOU] A זכרון OF SOUNDING THE CORNET — a mention (זכרון) of Biblical verses which speak of the Divine remembrance and Biblical verses which have reference to the blowing of the Shofar (a ram’s horn) on the occasion of important historical events (Sifra; Rosh Hashanah 32a) that I may recall to memory (זכרון) for you the offering (lit., the “Binding”) of Isaac in whose stead a ram was offered (cf. Rosh Hashanah 16a) having been caught by its horn (שופר‎).