'My Covenant' in the Bible

“For the mountains may be removed and the hills may shake,But My lovingkindness will not be removed from you,Nor will My covenant of peace be shaken,”Says the Lord who has compassion on you.

This is what the Lord says,“To the eunuchs who keep My SabbathsAnd choose what pleases Me,And hold firmly to My covenant,

“Also the foreigners who join themselves to the Lord,To minister to Him, and to love the name of the Lord,To be His servants, everyone who keeps the Sabbath without profaning itAnd holds fast to My covenant [by conscientious obedience];

“As for Me, this is My covenant with them,” says the Lord: “My Spirit which is upon you [writing the law of God on the heart], and My words which I have put in your mouth shall not depart from your mouth, nor from the mouths of your [true, spiritual] children, nor from the mouth of your children’s children,” says the Lord, “from now and forever.”