'On the First Day of the Week' in the Bible

Now upon the first day of the week, very early in the morning, they came unto the sepulcher, bringing the spices which they had prepared, and certain others came with them.

And upon the first day of the week, when the disciples came together to break bread, Paul preached unto them, ready to depart on the next day; and continued his speech until midnight.

Upon the first day of the week let every one of you lay by him in store, as God has prospered him, that there be no gatherings when I come.