'First Day' in the Bible

And the first day of the feast of Unleavened Bread, the day for killing the paschal lamb, his disciples asked him, "Where do you want us to go and make preparation for you to eat the Passover?"

And very early in the morning, on the first day of the week, they came to the tomb as the sun was rising;

So they went out, and ran from the tomb, for they were trembling and amazed; and they said nothing to any one, for they were afraid??9 Now after his resurrection, early on the first day of the week he appeared first to Mary Magdalene, from whom he had driven out seven demons.