Romans 1:9-10 : For God is my witness, whom I serve in my spirit in the gospel of his Son, how unceasingly I make mention of you, always in my prayers making request, if by any means now at length I may be prospered by the will of God to come unto you. "For God is my witness" was a solemn declaration; he was not making the statement lightly. Perhaps some Judaizing teacher was at Rome and was trying to discredit Paul by telling the brethren that Paul's oft-repeated promises to come were never intended to be fulfilled. So Paul declares that God was witness to the fact that always in his prayers for them he had requested that he might be permitted by the will of God to come to them. He would have them know that, though he could make plans to come, his movements were subject to God's will and this should remind us that we should not leave God out of our plans and purposes. On this point James says: "Come now, ye that say, Today or tomorrow we will go into this city, and spend a year there, and trade, and get gain: whereas ye know not what shall be on the morrow. What is your life? For ye are a vapor that appeareth for a little time, and then vanisheth away. For that ye ought to say, If the Lord will, we shall both live, and do this or that" (James 4:13-15). "Whom I serve in my spirit in the gospel of his Son." The spirit, the inner man, frequently called "the heart," is the source of our deeds of acceptable service; and this service of the spirit, to be acceptable, must be in the gospel--that is, in the things the gospel requires. In John 4:24, Jesus says: "God is Spirit and they that worship him must worship in spirit and truth." The spirit, the heart, must be in the worship, and the worship must be in the way truth marks out.