“But on the night immediately following, the Lord stood at his side and said, ‘Take courage; for as you have solemnly witnessed to My cause at Jerusalem, so you must witness at Rome also.’” (v.11)
Back in chapter 22 Paul was giving a sermon to a large crowd in Jerusalem. He tells of his Jewish upbringing and background (v.3). He explained how he persecuted Christians (v.4-5). Then he begins to explain the supernatural experience he had on his way to Damascus (vv.6-11), and his response to that experience (vv.12-15).
However, when Paul told the crowd that Jesus had spoken to him while in prayerful trance to "leave Jerusalem for they will not receive your testimony concerning Me" (v.18), and "Depart, for I will send you far from here to the Gentiles" (v.21), the crowd raised their voices and said, “Away with such a fellow from the earth, for he is not fit to live!” Then, as they cried out and tore off their clothes and threw dust into the air and began rioting (vv.22-23).
Paul was then placed in a Roman jail (for his own protection from the crowd), and was once again a prisoner in chains where we see a hint that he felt like hope was fading. He would have been remembering those who had warned him "not to go up to Jerusalem" (Acts 21:12). He had gone, but his decision now seemed less sure, because going had led to confinement and isolation, which left little opportunity for him to speak of His Lord.
It was at this low point in his life that the Lord appeared and told him, “Be of good cheer; you must also witness at Rome.” Loose translation, Paul would not "rot" in that place but instead, would eventually be sent to the capitol of the Roman Empire and witness to Cesar.
This reminds us that the LORD has a plan for ALL his children who are in the difficult circumstances in this life. No matter WHAT happens “be of good cheer.” the Lord LOVES you and will never leave you, nor forsake you! And, He has a plan for your life.
The Truth: “The Lord of hosts is with us; The God of Jacob is our refuge.” (Psalm 46:7)