For this is as the waters of Noah This covenant of grace and peace made with thee shall be as certain and perpetual as that which I made with Noah, that there should never be another flood of waters to drown the world. So have I sworn that I would not be wroth with thee Namely, so as I have been, or so as to forsake thee utterly. For the mountains shall depart, &c. The mountains and hills shall sooner depart from their places than my kindness shall depart from thee. Nay, the time will come when all the mountains shall depart, and all the hills be removed, and even the whole earth, and all the works that are therein, shall be burned up, but then the covenant of peace between God and his church shall continue in the everlasting happiness of all the true and spiritual members of it. God will not cast off the Christian Church, as he cast off the Church of the Jews; the new covenant being established upon better and surer promises than the old; see Hebrews 8:6-7. Saith the Lord that hath mercy on thee Who acts thus toward thee, not for thy merits, but through his own grace and mercy.
Related Commentaries of Isaiah 54:9
Isaiah 54:9-10
9 For this is as the waters of Noah unto me: for as I have sworn that the waters of Noah should no more go over the earth; so have I sworn that I would not be wroth with thee, nor rebuke thee.
10 For the mountains shall depart, and the hills be removed; but my kindness shall not depart from thee, neither shall the covenant of my peace be removed, saith the LORD that hath mercy on thee.