Ramban on Bo 13:6

English: AND IN THE SEVENTH DAY SHALL BE A FEAST TO THE ETERNAL. This means that they are to bring their Festival-offering on the seventh day [of Passover] and are not to delay it any longer, for after that, one can no longer make amends for it. However, as far as the Festival-offering 383 Upon going up to the Sanctuary on the three Festivals of Pesach, Shevuoth, and Succoth, one is obligated to bring a Festival peace-offering. (See “The Commandments,” Vol. I, pp. 60-61). That Festival-offering should be brought on the first day of the festival and not later than on the seventh day of Passover or on Shmini Atzereth , which is the eighth day of Succoth. The Festival of Shevuoth, though only one day, has a similar seven-day extension period (Chagigah 9 a). is concerned, amends can be made for the first day of the festival all seven days. Both [the first and seventh] days of Passover are alike with