"Note, Praying friends are valuable friends; it is good to have an intimacy with and an interest in those that have fellowship with God and an interest at the throne of grace; and it well becomes the greatest and best of men to desire the assistance of the prayers of others for them. St. Paul often entreats his friends to pray for him. Thus we must show that we put a value upon our friends, upon prayer, upon their prayers."
(Source: Matthew Henry's Commentary).