Romans 15:12-13
Going back in this chapter to verse 7 will help with context. Paul is writing to the new Christians in Rome. These ARE the Gentiles. Gentiles simply means not Jewish. (Which also means us!) The entire Old Testament is about Israel and the Jewish people’s lives. All along, God had plans to reach the world with His salvation. He wants to be in relationships with everyone.
In verses 9-13 here, Paul is quoting the Old Testament showing proof that God intended for the Gentiles to be saved. This is one of the coolest things about the Bible and one way to know it's true. Anything written hundreds of years before would not match later had a mere human written it. God proves Himself true by these New Testament writers quoting the Old Testament.
God is our source of hope and when we trust Him completely, with all we have, then we will have joy and peace in abundance! Trying to rely on ourselves or another human being for things that only God can do leads us down a path of despair. You are GOING to get hurt & upset only trusting humans. We have the Holy Spirit inside of us and we need to learn to trust Him too. He will lead, guide, & direct us as well. Do you trust Him?