Sabbath - a weekly festival having its origin in the fact that God made the world in six days and was arrested on the seventh.

If we do not need to worship God six days in the week why do we need to worship him on the seventh?

Six days may work be done; but in the seventh is the sabbath of rest, holy to the LORD: whosoever doeth any work in the sabbath day, he shall surely be put to death.

They continued but six days under this course, having consumed the quantities that could be spared.

I exercise six days a week for one hour in the morning.

You can't have a belief system on Sunday and not live it the other six days.