George Fox preaches about the unity and obedience among the early apostles and disciples, emphasizing their willingness to be sent and their submission to the guidance of the Holy Spirit. The sermon highlights the importance of exhortation, encouragement, and support within the church community, as seen through the actions of Paul, Barnabas, and other early Christian leaders. It also stresses the need for diligence, obedience, and love in fulfilling God's work and ministering to one another, as exemplified by the apostles' interactions and instructions to various churches and individuals.