One of the difficulties in Isaiah is the change of speaker. Where the chapter begins with the voice of the Lord, now we are presented with the voice of a servant of God. This servant can be considered the same as that discussed for 1 Nephi 20-21. With the clear Messianic foreshadowing in verse 6, the speaker is Jesus in his role of mediator.
In this verse, the servant indicates that God has given him direction in his message to Israel. In this case, while Israel is distant from the Lord ("when ye are weary") the Lord nevertheless watches over Israel ("he waketh morning by morning") and has sent the servant to tell them what they need ("he waketh mine ear to hear as the learned.")