21 “As for me, this is my covenant with them,” says the LORD. “My Spirit, who is on you, will not depart from you, and my words that I have put in your mouth will always be on your lips, on the lips of your children and on the lips of their descendants—from this time on and forever,” says the LORD.

Read Isaiah 59:21 Using Other Translations

As for me, this is my covenant with them, saith the LORD; My spirit that is upon thee, and my words which I have put in thy mouth, shall not depart out of thy mouth, nor out of the mouth of thy seed, nor out of the mouth of thy seed's seed, saith the LORD, from henceforth and for ever.
"And as for me, this is my covenant with them," says the LORD: "My Spirit that is upon you, and my words that I have put in your mouth, shall not depart out of your mouth, or out of the mouth of your offspring, or out of the mouth of your children's offspring," says the LORD, "from this time forth and forevermore."
“And this is my covenant with them,” says the LORD . “My Spirit will not leave them, and neither will these words I have given you. They will be on your lips and on the lips of your children and your children’s children forever. I, the LORD, have spoken!