In verse 3 the Lord had told Isaiah that through his mission the Lord would be glorified. But Isaiah said that he told the Lord that so far his labor had been in vain. He had labored with great diligence, but the people were not converted, neither were they giving him a respectful hearing. In Isaiah 50:5-6, Isaiah describes how he had been beaten with sticks, his beard had been pulled and his face had been spat upon. He said that it was as though he had spent his strength for naught, and his work had been in vain. Nevertheless, he said he will set face like flint, and perform the mission God has given him.
5. And now, saith the Lord -- that formed me from the womb that I should be his servant, to bring Jacob again to him -- though Israel be not gathered, yet shall I be glorious in the eyes of the Lord, and my God shall be my strength.
In this verse the prophet Isaiah states that the Lord has revealed something to him which has provided a great comfort and encouragement in spite of the persecution he has suffered. He has said the Lord has told him that even though Israel will not repent and gather together in righteousness during Isaiah's day, yet the time will come when the words of Isaiah will be completely vindicated and he will be glorious in the eyes of the Lord. In the next verse the Lord describes how this will come about.