Isaiah chapter 50 contrasts the sin of Israel with the obedience of the Messiah. Since that is the case, Isaiah 50:4 is certainly a verse concerning the fitness of the righteous Servant to do the will of the Father. But, even though it is about Jesus, it is something that I want to be true of myself as well:
The Lord Yahweh has given me the tongue of those who are taught, that I may know how to sustain with a word him who is weary. Morning by morning He awakens; He awakens my ear to hear as those who are taught.
It is certainly not a bad thing to want what is true of Jesus to be true of me. We are predestined to be conformed to His image after all (Romans 8:29). Not only that, but specifically in the case of Isaiah 50:4, we have Jesus telling Peter over and over again in John chapter 21 that He wants him to "feed His sheep". In order to prepare proper meals for God's people, His ministers need to be able to "hear as those who are taught" and we need to "know how to sustain with a word him who is weary."
Oh Lord, please fulfill this verse in my life and in the lives of all of those who are partners with me in the work of the gospel. Grant us Your wisdom and a knowledge of Your Truth. Let our tongues only ever speak to others that which is holy and right. May we know how to comfort and sustain the weary. Give us open ears, discerning minds, and loving hearts to do Your work in Your people for the sake of Your praise in Jesus' name.