'First Day' in the Bible

On the first day of the week, very early in the morning while it was still dark, Mary of Magdala went to the tomb, and she saw that the stone had been removed from the tomb.

In the evening of that same first day of the week, even with the doors of the room bolted where the disciples had met for fear of the Jews, Jesus went in and stood among them and said to them, "Peace be with you!"