In the Bible Sunday is always referred to as the "First Day of the week not the 7th or Sabbath day. Also in Genesis 2:2 - And on the seventh day Elohim ended his work which he had made; and he rested on the seventh day from all his work which he had made. Genesis 2:3 - And Elohim blessed the seventh day, and sanctified it: because that in it he had rested from all his work which Elohim created and made Yahweh literally Rested on the Sabbath day after creating the world and even Sanctified it! The Sabbath is created for us so we can rest from the work we have done during the week. It also recharges us spiritually. We have the sabbath to focus on YAHWEH and to learn and grow in the word! Paul in 1 Corinthians 16:1-2 Now concerning the collection for the saints, as I have given order to the assemblies of Galatia, even so do ye. Upon the first day of the week let every one of you lay by him in store, as hath prospered him, that there be no gatherings