Becouse Set was bad.
Set and Osiris were brothers. Osiris was the king of Egypt. And all the people loved him. But Set hated his brother, Osiris. He wanted to be the king of Egypt, so he plotted to kill Osiris.
Set planned a big party. For the event, he built a big beautiful box. It was made of the best wood and decorated with paint and gold. The box was the perfect size for Osiris to fit inside. Set told people at the party about a special game he had planned. He said he would give the beautiful box to anyone who could fit inside it. A few people tried, but no one could fit into Set’s box.
Finally, Osiris tried to fit into the box. And he fit perfectly! But as soon as Osiris was inside, Set slammed the box closed. He sealed the box with hot metal so that it would not open. And he threw the box, with Osiris in it, into the Nile River where Osiris died.
it is only a brincadeirinha. See you.