Isaiah
Isaiah 59:21BSB·traditional attribution

“As for Me, this is My covenant with them,” says the LORD. “My Spirit will not depart from you, and My words that I have put in your mouth will not depart from your mouth or from the mouths of your children and grandchildren, from now on and forevermore,” says the LORD.

Matthew Henry Presbyterian @wholebiblehenry

How sin abounded we have read, to our great amazement, in the former part of the chapter; how grace does much more abound we read in these verses. And, as sin took occasion from the commandment to become more exceedingly sinful, so grace took occasion from the transgression of the commandment to appear more exceedingly gracious. Observe, I. Why God wrought salvation for this provoking people, notwithstanding their provocations.

Commenting on Isaiah 59:16-21

John Gill Reformed Baptist @doctorgill

As for me, this is my covenant with them, saith the Lord,.... Which shall be manifested and made good to them that repent of their sins, and, believe in Christ; and to whom the particular blessing of it shall be applied, the forgiveness of their sins; see Rom 11:27, my Spirit which is upon thee, and my words which I have put in thy mouth...

Jamieson-Fausset-Brown Reformed @jfbcommentary

covenant with them . . . thee--The covenant is with Christ, and with them only as united to Him (Heb 2:13). Jehovah addresses Messiah the representative and ideal Israel. The literal and spiritual Israel are His seed, to whom the promise is to be fulfilled (Psa 22:30). spirit . . . not depart . . . for ever-- (Jer 31:31-37; Mat 28:20).