17 The words of the wise: Incline your ear and hear my words, and apply your mind to my teaching;
LISTEN! THINK! “Incline your ear” means to be purposeful, intent, to lean in as one does when trying to hear a soft voice over background noise. “Lean in and listen,” God says. “Then, go and think about what I’ve said. USE YOUR HEAD!” Faith comes when we set aside or struggle through all the other voices around us to hear what GOD has said. It takes faith to make that a priority – faith that it is worth the time to hear these archaic writings from generations and cultures long past. To Hear is itself an act of faith. Then, our thinking function comes in – first believe, then reason.

18 for it will be pleasant if you keep them within you, if all of them are ready on your lips.
“Keep MY words with you.” In others words, learn them, commit them to memory, write them on your heart. Don’t just listen – memorize and soak in deep. Have them in you and be ready and able to speak them as Jesus did when tempted by Satan in the Wilderness (Mt 4). Jesus did not have a Bible with Him – He kept the words within Him. We confront the same temptations and obstacles, and need the very same resource to succeed.

19 So that your trust may be in the Lord, I have made them known to you today yes, to you.
As a result, our trust in God will increase and be strengthened – some trust (faith) is necessary to put the work in to begin with – and the fruit of our labor is increasing trust.

20 Have I not written for you thirty sayings of admonition and knowledge, 21 to show you what is right and true, so that you may give a true answer to those who sent you?
HMMM… I’m not sure about this last phrase: “that you may give a true answer to those who sent you” Perhaps it is this: that we are sent out, and give an answer on our return. Jesus has called me to be His disciple, and then GOD (three-in-one – there for a “they”) has sent me out, and at some time I will be required to give an account to the LORD of the vineyard, the LORD of the harvest. In the wisdom and knowledge of God, I will know what is right, and be empowered by the Spirit to choose it, and will thus be able to give an account on my return.

“What have you done with what I gave to you?” This is the question that will come from the LORD.