'First Day' in the Bible

On the first day of unleavened bread, when they sacrificed the Passover, his disciples asked him, "Where do you want us to go and prepare that you may eat the Passover?"

Very early on the first day of the week, they came to the tomb when the sun had risen.

Now when he had risen early on the first day of the week, he appeared first to Mary Magdalene, from whom he had cast out seven demons.