'First Day' in the Bible

And the first day of unleavened bread, when they slew the passover, his disciples say to him, Where wilt thou that we go and prepare, that thou mayest eat the passover?

And very early on the first day of the week they come to the sepulchre, the sun having risen.

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