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. This is my covenant with them "This is the covenant which I make with them" - For אותם otham, them, twenty-four MSS., (four ancient), and nine editions have אתם ittam, with them.
My Spirit that is upon thee - This seems to be an address to the Messiah; Kimchi says it is to the prophet, informing him that the spirit of prophecy should be given to all Israelites in the days of the Messiah, as it was then given to him, i.e., to the prophet.
And my words which I have put in thy mouth - Whatsoever Jesus spoke was the word and mind of God himself; and must, as such, be implicitly received.
Nor out of the mouth of thy seed - The same doctrines which Jesus preached, all his faithful ministers preach; and his seed - genuine Christians, who are all born of God, believe; and they shall continue, and the doctrines remain in the seed's seed through all generations - for ever and ever. This is God's covenant, ordered in all things and sure.
Commentary on the Bible, by Adam Clarke [1831].