'Week' in the Bible

Now on the first [day] of the week, Mary Magdalene came to the tomb early, [while it] was still dark, and saw the stone had been taken away from the tomb.

Now [when it] was evening on that day--the first [day] of the week--and the doors had been shut where the disciples were because of fear of the Jews, Jesus came and stood in their midst and said to them, "Peace to you."