To put it bluntly, there’s nothing wrong with “Sunday worship.” We can “worship” on any day we want – as a matter of fact, we’re TOLD to be in constant worship. (Psalm 113:3, 72:15, 34:1; Hebrews 13:15; Revelation 4:8, etc.)
However, YHWH’s commanded Day of REST has always been the “7th Day” – which, on our Gregorian calendars – happens to fall on Saturday. It is the day He commanded us to take a break from our weekly work and just REST our weary bodies….
Take a look at how the following verses talk about REST, and not necessarily “worship” or congregating. (Yes, worshiping and congregating falls right in line with "Shabbat", but that doesn't mean we have the right to tell anyone to NOT “worship” on Sunday - which is what many Hebrew Rooters are posting in their attempts to lead Christians to the Truth of Torah. The simple fact is, while we are to REST one day a week, our "worship" of YHWH should never cease.)
Scripture explains that YHWH Himself “rested” on the 7th day….
Genesis 2:1 Thus the heavens and the earth were finished, along with everything in them. 2 On the seventh day God was finished with his work which he had made, so he rested on the seventh day from all his work which he had made. 3 God blessed the seventh day and separated it as holy; because on that day God rested from all his work which he had created, so that it itself could produce. (CJB)
And here we see YHWH telling HIS people that His Shabbats are not only a Day of REST, but a SIGN between Him and His people! (And by the way, if you're ignoring that "sign" then WHOM are you worshiping?)
Exodus 31:16 The people of Isra'el are to keep the Shabbat, to observe Shabbat through all their generations as a perpetual covenant. 17 It is a sign between me and the people of Isra'el forever; for in six days ADONAI made heaven and earth, but on the seventh day he stopped working and rested.'"
Exodus 20:8 "Remember the day, Shabbat, to set it apart for God. 9 You have six days to labor and do all your work, 10 but the seventh day is a Shabbat for ADONAI your God. On it, you are not to do any kind of work -not you, your son or your daughter, not your male or female slave, not your livestock, and not the foreigner staying with you inside the gates to your property. 11 For in six days, ADONAI made heaven and earth, the sea and everything in them; but on the seventh day he rested. This is why ADONAI blessed the day, Shabbat, and separated it for himself.
Ezekiel 20:11 I gave them my laws and showed them my rulings; if a person obeys them, he will have life through them. 12 I gave them my shabbats as a sign between me and them, so that they would know that I, ADONAI, am the one who makes them holy.
Isaiah 56: 2 Happy is the person who does this, anyone who grasps it firmly, who keeps Shabbat and does not profane it, and keeps himself from doing any evil. 3 A foreigner joining ADONAI should not say, "ADONAI will separate me from his people"; likewise the eunuch should not say, "I am only a dried-up tree."
4 For here is what ADONAI says: "As for the eunuchs who keep my Shabbats, who choose what pleases me and hold fast to my covenant: 5 in my house, within my walls, I will give them power and a name greater than sons and daughters; I will give him an everlasting name that will not be cut off.
6 "And the foreigners who join themselves to ADONAI to serve him, to love the name of ADONAI, and to be his workers, all who keep Shabbat and do not profane it, and hold fast to my covenant, 7 I will bring them to my holy mountain and make them joyful in my house of prayer; their burnt offerings and sacrifices will be accepted on my altar; for my house will be called a house of prayer for all peoples."
Isaiah 58: 13 If you hold back your foot on Shabbat from pursuing your own interests on my holy day; if you call Shabbat a delight, ADONAI'S holy day, worth honoring; then honor it by not doing your usual things or pursuing your interests or speaking about them. 14 If you do, you will find delight in ADONAI - I will make you ride on the heights of the land and feed you with the heritage of your ancestor Ya'akov, for the mouth of ADONAI has spoken."
There are many more scriptures like the above that describe YHWH’s Shabbat, but NONE of them suggest one cannot WORSHIP on “Sunday”…