The Women - 4:47
People of the Book! Believe in what We have sent down confirming what is with you, before We turn away some faces and send them into exile and curse them as We cursed the people of Saturday. Allah´s command has always been practiced.
Who are the people of Saturday?
The Cow/2:63
"We once took a promise from you when We raised Mount Sinai over you, saying: "Hold fast to what We have given you and remember what is in it, that you may be protected"."
The Cow/2:64
But after that you turned away. Had it not been for Allah´s bounty and mercy upon you, you would have lost.
The Cow/2:65
"Surely you know those of you who transgressed the prohibition of Saturday. We said to them: "Be despicable monkeys"."
The Heights/7:163
Ask them about the people by the sea. They used to violate the prohibition of work on Saturday. On the day when they observed Saturday their fish came to them in abundance, but on the day when they did not observe Saturday no fish came to them. Thus did We test them because they went astray.