Rashi on Leviticus 19:6/רש"י על ויקרא י״ט:ו׳

1ביום זבחכם יאכל ON THE DAY YE SACRIFICE IT [SHALL IT BE EATEN] — This means, when ye slaughter it (וכי תזבחו) slaughter it (תשחטהו =תזבחהו) having in mind the period which I have already fixed for you as that within which it must be eaten (that which is mentioned already Leviticus 7:16).