'First Day' in the Bible

And the first day of Unleavened Bread, when they killed the passover, His disciples said to Him, Where do You desire that we go and prepare that You may eat the passover?

And very early in the morning, the first day of the week, they came upon the tomb, the sun having risen.

And when Jesus had risen early the first day of the Sabbath, He appeared first to Mary Magdalene, out of whom He had cast seven demons.