Isaiah 56:2, 6

Blessed is the man who does this, and the son of man who holds it fast, who keeps the Sabbath, not profaning it, and keeps his hand from doing any evil.”

“And the foreigners who join themselves to the LORD, to minister to him, to love the name of the LORD, and to be his servants, everyone who keeps the Sabbath and does not profane it, and holds fast my covenant