v1: Addressed to those who follow after righteousness, who seek the Lord. The Rock, Deut 32.15, to which Israel belonged, Ex 4.22. Since we are hewn from a rock, we should be like the rock. Isaiah implies that there are few who follow after righteousness.
v2: Abraham, called by God; God's only choice; therefore Israel is God's only nation. Abraham, as promised by God, was made many, and blessed abundantly. The great wealth he accumulated was no accident, for he enjoyed God's blessing. But Abraham provides an important example, in that his faith persevered over many years. Blessing was not immediate. He had to learn patience.
v3: Barrenness replaced by fruitfulness, 44.3. The theme of comfort for Zion, see v11-12, 16, 22.
v4-6: Promises of blessings to come; justice, righteousness, salvation; as the things around us vanish away, but the things of God are eternal; see 40.6-8; Ps 102.25-27; and these things are referred to in the NT, Heb 1; 1 Pet 1; 2 Pet 3.
v7-8: God's people endure the reproach of men now, but God's promises will never fail. Our part is to trust in Him. In Him alone are the blessings of righteousness and salvation.
v9-10: In response to the declarations of God's character, the prophet prayed, "Are you not the one...?" (See Judg 6.13) He asked the Lord to demonstrate His character again; just as He had defeated Egypt (Rahab, the serpent, Ps 89.10), and just as He made a road through the Red Sea. He acted in might on behalf of His redeemed people; will He not do the same again?
v11: The future promises are that those He has redeemed will return to Zion, full of joy, which can never be removed, expressed in singing. This is God's answer to the prayer; He has a future for His people, and will bring them to Zion in safety.
v12-13: In difficult times, Israel forgot God and His precious promises, and learned to fear mortal man. But God remained true. He urged His people not to be afraid.
v14-16: Times of fear and doubt, "For I am the Lord your God," He reminds them. Nothing is too hard for Him. In particular, He has made promises to His people, and set them apart, "I have put my words in your mouth and covered you with the shadow of my hand...'You are my people;'"
There are times when we endure fear and doubt, when we suffer for the cause of Christ. These verses encourage us to look to Him, the faithful One, the unchangeable One. We must be reminded of His promises towards us.
v17-20: God's fury finished; these words are future, looking back. Jerusalem will have drunk the cup of God's fury, will have suffered the loss of comfort (Lam 1.17), with no one to care; even her bravest "sons" faint and are captured, because of the Lord's anger, Lam 2.21. The nation bore the punishment deserved.
The testimony later was that they had been punished less than their sins deserved, see Ezra 9.13.
v21-23: The nation, once drunk with the cup of God's wrath, is once more restored to God, enjoying His protection. The nation will never again drink His wrath. Indeed, those who attack God's people will suffer His wrath.