The mission of the Apostles'

Jesus left a command for all of his followers-To preach and teach everyone the truths from The Bible, with the aim of making disciples. (Matthew 28:19-20) He also emphasized being "witnesses" of him throughout the surrounding lands and eventually the world. (Acts 1:8) This meant that the apostles would take the lead in letting people know the significance of Jesus' role in Jehovah God's purposes, as well as some of the major events they bore witness to, such as the miracles he performed and even his resurrection.

(New World Translation of the Holy Scriptures)