Deuteronomy 5:32

It is interesting to study the way God extended His guidance to these early messengers of the Cross. It consisted mainly in prohibiting their movement when they attempted to take a course other than the right one. When they wanted to turn to the left, toward Asia, He stopped them. When they sought to turn to the right, toward Bithynia in Asia Minor, He stopped them again.

In his later years, Paul would do some of his greatest work in that very region, yet now the door was closed before him by the Holy Spirit. The time was not yet ripe for the attack on these apparently impregnable bastions of the kingdom of Satan. Apollos needed to go there first to lay the groundwork. Paul and Barnabas were needed more urgently elsewhere and required further training before undertaking this responsible task.