'My Covenant' in the Bible

For thus sayeth the LORD, first unto the gelded that keepeth my Sabbath - namely, that holdeth greatly of the thing that pleaseth me, and keepeth my covenant -

Again, he sayeth unto the strangers that are disposed to stick to the LORD, to serve him, and to Love his name: That they shall be no bondman. And all they, which keep themselves, that they unhallow not the Sabbath - namely, that they fulfill my covenant -