The first verse in this chapter uses poetic language to describe the love of the Savior as being mother-like—unbreakable. The phrase "thus saith the Lord" had been used twice in 6:17 and it is used twice again in 7:1. We know to pay close attention when the prophet says, "thus saith the Lord." Here it emphasizes that, like a mother, Jesus Christ will not cast off His covenant children. As the poetic emphasis grows, so too does the promissory certitude that he will stand immoveable, to a greater degree than even a mortal mother is capable. If there is separation, it will be due to the choice of man, and not to God’s withdrawal.
Isaiah likens our covenant with God to a marriage covenant. Under the Law of Moses, a man could find some offense in his wife and say, "I divorce thee" and give her a paper of divorcement, which would end the marriage. But the Lord has not done that. If a person had huge debts, they would sometimes sell their children into slavery to the creditors. But the Lord has not done that, and He will not do that.
Look at verse 2. There it says, "O house of Israel is my hand shortened at all that it cannot redeem or I have no power to deliver?" Is the Lord’s hand shortened? If you look back at 2 Nephi 6:6, the Lord says "I will lift up my hand to the gentiles." What does it mean to "lift up the hand?" When the Israelites were wandering through the wilderness, they had several conflicts with other groups. On one occasion Moses had to literally hold his hands up in order for his people to win a battle. For this reason, he had to have two counselors of sorts, one on each side of him to hold up an arm. Christ is going to hold up his hand to the gentiles—he is going to extend to them his protective authority as long as possible.
Indeed, the Lord will send his Servant who has been given knowledge (7:5). The Servant was not rebellious, but instead would give his back to the smiter, the plucker, the shamer, and the spitter (7:6). He would set his face like flint, and would not be ashamed (7:7). And thus the Servant will be justified in the face of his accuser. They will stand together to be judged, and those who condemn him will wax old as a garment, and a moth shall eat them (7:9). These words of Isaiah, quoted by Jacob in the city of Nephi, will reverberate four hundred years later, also in the city of Nephi, when Abinadi will warn king Noah that his life will be valued as a garment in a furnace because of his wicked ways.
Leland Gentry, "God Will Fulfill His Covenants with the House of Israel," in Second Nephi: The Doctrinal Structure, The Book of Mormon Symposium Series, Volume 3, ed. Monte S. Nyman and Charles D. Tate, Jr. (Provo, UT: Religious Studies Center, Brigham Young University, 1989), 167–172.