Paul saw himself as "poured out" as an offering (Greek spendo) on the "sacrifice and service" of these precious friends. This special word is used only one other time, when Paul was "ready to be offered" at his death (2 Timothy 4:6).
Paul’s ministry among the Philippians resulted in the godly lifestyle of the church. They became sacrifices (Greek thusia) much like the Lord Jesus "hath given himself for us" (Ephesians 5:2) and as we are all told to "present |our| bodies a living sacrifice, holy, acceptable unto God, which is |our| reasonable service" (Romans 12:1).
The service that is commended of the Philippians is a public service undertaken at one’s own expense (Greek leitourgia). Several men in the church at Antioch were noted for their ministry (Acts 13:2 uses the same word), and some in Macedonia and Achaia were also acknowledged for giving contributions to the saints at Jerusalem (Romans 15:26-27).
Paul’s joy and rejoicing at the godly activity of the faithful saints at Philippi is the key to understanding the tone of the entire book. He had "poured out" himself, even being "shamefully entreated" during his ministry there (1 Thessalonians 2:2). Yet while writing this poignant letter back to the church, he gives joyful greetings to them at the certain knowledge that his ministry among them has resulted in their sacrifice and service.
Would God that all of us could see our offerings for the sake of others with the same passionate expectation. Often our Lord calls on us to give of ourselves in selfless ways so that others may learn from our example. Sometimes, we must even pour out our own souls (1 Thessalonians 2:8) for the sake of the gospel. HMMIII