Sefer HaChinuch ספר החינוך

The commandment of resting on the first day of Pesach: To rest on the first day of Pesach, as it states about it (Leviticus 22:7), “On the first day, a holy occasion.” And about all about which it is stated in the Torah, “a holy occasion,” they, may their memory be blessed, explained (Sifra, Emor, Chapter 12:4), “Make it holy.” And the content of its holiness is that no work be done on it, except for that which is specific to eating; as the verse elucidated (Exodus 12:16), “but that which is eaten by every soul, that alone shall be done for you.” And the proof that the rest of the holiday is considered a positive commandment is their, may their memory be blessed, saying (Shabbat 25a), “This ‘shabbaton’ is a positive commandment.” And we learn from now that in every place that shabbaton is stated in the Torah with regards to a holiday, it is a positive commandment. And [what] also appears much in the Talmud is, “The holiday is a positive commandment and a negative commandment.”

It is from the roots of the commandment [that it is] in order that we think about the content of the holiday in the miracle that was done for us on it, and that we praise and laud in our thoughts the One, blessed be He, Who commanded us about it and did miracles for us at this time. And if a man is preoccupied in his work, he will not be free to think about anything. And we will further write at length about its root and its laws in the negative commandment of work on the holiday in this Order (Sefer HaChinukh 288) with God’s help.

And [it] is practiced in every place and at all times by males and females. And one who transgresses it and does work not for the needs of food for the soul has violated this positive commandment, besides that he violated a negative commandment - as we will write in its place.

The laws of the commandment are elucidated in [Beitzah]. (See Mishneh Torah, Laws of Rest on a Holiday 1.)