I don't think anyone, including Abraham, was commanded to keep the Sabbath until Exodus 31:
Sabbath was a special sign of the covenant between God and the Israelites after exiting Egypt.
In the NT, Jesus healed on the Sabbath in John 5:
According to the Jewish authority, Jesus broke the Sabbath and Jesus told P1 to break the Sabbath. The Pharisees saw sins as external behaviors. See e.g., The 39 Categories of Sabbath Work Prohibited By Law. Jesus shifted the focus to the heart where sin originated (Matthew 5:28).
Paul had this to say in Romans 14:
Should we keep the Sabbath?
According to Paul, it is up to the individual believers. Further, we should not judge others about Sabbath, Colossians 2:
If you keep the Sabbath, are you going to keep the punishment?
Numbers 15:
The weekly Sabbath is only a shadow of the true Sabbath rest. Once we have the true reality, there is no need to chase after the shadows.
As I said, I saw nothing positive about regular Sunday Services.