O.k., let's see what they did after the resurrection...

First Jesus say pray that your flight be not in the winter and on the Sabbath day. Why would He warn followers if the Sabbath wasn't binding anymore? This is 70 AD that He was talking about....

Also, when He was buried, the woman stopped working on His body because the Sabbath drew on. They kept Sabbath and He did even in death.

The apostles kept Sabbath, look at Paul and the 'reasoning' he did on the Sabbath. There ws times when both Jews and Gentiles came to worship on the Sabbath and even said they would return the following Sabbath.

I know Acts 20:7 is the big claim, but all that said was that they gathered on late Saturday night (first day of the week was as soon as the sunset) so they were preaching from Sabbath into the late hours of the night.

And appearing to His disciples doesn't make a day holy. The day is sanctified and made holy by Christ in Genesis 2.

It's interesting of what Catholics do say about Sabbath....And you can Google it to confirm it if you wish:

from the Convert’s Catechism of Catholic Doctrine by Reverend Peter Giermann.

Question: Which is the Sabbath day?

Answer: Saturday is the Sabbath day.

Question: Why do we observe Sunday instead of Saturday?

Answer: We observe Sunday instead of Saturday because the Catholic Church in the Council of Laodicea transferred the solemnity from Saturday to Sunday.

This is what I mean when I say we need to be very careful we are following what God says, and not what man says.