Rashi on Deuteronomy 25:19/רש"י על דברים כ״ה:י״ט

1תמחה את זכר עמלק THOU SHALT WIPE AWAY THE REMEMBRANCE OF AMALEK, — both man and woman, infant and suckling, ox and sheep (a quotation from I Samuel 15:3, stating how the Amalekites were to be destroyed), so that the name of Amalek should never again be mentioned even in connection with a beast, in that one could say: “This beast belonged to Amalek” (Pesikta Zutrata).