Those in Messiah are Israyl:
Romans 9:6-8, "However, it is not as though YHWH's plan had failed. For it is not everyone who is a descendant of Yisra’yl who belongs to Yisra’yl. Nor, just because they are his descendants, are they all Abraham's children; but: In Isaac will your seed be called. That is, it is not those who are the children of the flesh who are YHWH's children; but it is the children of the promise who are regarded as Abraham's seed."
Psalms 105:6-10, “O seed of Aḇraham His servant, Children of Ya‛aqoḇ, His chosen ones! He is יהוה our Strength; His right-rulings are in all the earth. He has remembered His covenant forever, The Word He commanded, for a thousand generations, The covenant He made with Aḇraham, And His oath to Yitsḥaq, And established it to Ya‛aqoḇ for a law, To Yisra’yl – an everlasting covenant.”
The Sabbath is and was always for Hebrews and non-Hebrew Gentiles alike:
Isaiah 56:1-7, “Thus said יהוה, “Guard right-ruling, and do righteousness, for near is My deliverance to come, and My righteousness to be revealed. Blessed is the man who does this, and the son of man who becomes strong in it, guarding the Sabbath lest he profane it, and guarding his hand from doing any evil. And let not the son of the gentile who has joined himself to יהוה speak, saying, ‘יהוה has certainly separated me from His people,’ nor let the eunuch say, ‘Look I am a dry tree.’ For thus said יהוה, “To the eunuchs who guard My Sabbaths, and have chosen what pleases Me, and are holding onto My covenant: to them I shall give in My house and within My walls a place and a name better than that of sons and daughters – I give them an everlasting name that is not cut off. Also the sons of the gentile who join themselves to יהוה, to serve Him, and to love the Name of יהוה, to be His servants, all who guard the Sabbath, and not profane it, and are holding onto My covenant, them I shall bring to My set-apart mountain, and let them rejoice in My house of prayer. Their ascending offerings and their sacrifices are accepted on My altar, for My house is called a house of prayer for all the peoples.”
Mat 5:18, "I say to you; Unless heaven and earth passes away, one yodh; the smallest of the letters will in no way pass from the Law, until all things are perfected."
Revelation 21:1, "I saw a new heaven and a new earth, for the first heaven and the first earth had passed away."