The report of this came to the ears of the church in Jerusalem, and they sent Barnabas to Antioch. When he came and saw the grace of God, he was glad, and he exhorted them all to remain faithful to the Lord with steadfast purpose,” (Acts 11:22–23, ESV)

In this passage, Barnabas is sent by the church in Jerusalem to the church in Antioch because of the great number of people who were coming to faith in Antioch. Barnabas means “Son of exhortation; son of prophecy; son of consolation,” [Exhaustive Dictionary of Bible Names]and so he was.

Frederik Meyer writes of Barnabas:

Barnabas was a good man, and his unaffected piety enabled him to recognize at once that this movement was of God. All the signs of true conversion were present. He saw undoubted evidence of the grace of God, and pleaded with the new converts for tenacity and constancy. The secret of perseverance is in the phrase to cleave unto the Lord, v. 23. Acts 11:19 [Through the Bible Day by Day Devotional Commentary]

His message to the new believers: “Remain faithful to the Lord with steadfast purpose.” Young’s Literal Translation reads: “with purpose of heart to cleave to the Lord.” It is a good message for followers of Christ of any maturity, but especially for new believers.  We are prone to drifting away from the Lord due to sin, due to the human condition of generally being lazy creatures, and due to our own particular foibles.  Barnabas understands this proclivity, thus his encouragement to the new followers of Christ to cleave to him with all of their heart.