One of the reasons for conflict between ancient Egyptians and Jews (as reported by the Bible, iirc) was that Jews had their Sabbath every 7 days, while Egyptians would get their free day every 10 days. That's part of the reason why Jews decided to leave under Moses's leadership. Of course that was almost 1000 years after the Great Pyramid was built, if it even happened at all.

I think the term 'weekend' has connotations of not being religious, but sure, maybe weekends were invented earlier than the Industrial Revolution if the definition is generalized to 'a day when you don't work at the end of the week'.