The Fruit of Righteousness

In most of his epistles Paul asserts his position as an apostle of Jesus Christ as he writes with apostolic authority. However, as he writes to the beleaguered Philippians, he writes as a friend. His purpose is to encourage the Philippians in their walk with Christ in a cruel world. Although Paul was imprisoned in Rome, he wrote with joyful optimism. "Being confident of this very thing, that He who has begun a good work in you will complete it until the day of Jesus Christ" (1:6). He prayed that their love would abound and that they would be "filled with the fruits of righteous which are by Jesus Christ, to the glory and praise of God" (1:11). What are "the fruits of righteousness"?