John Calvin Commentary Acts 8:39

"And when they came up out of the water, the Spirit of the Lord caught away Philip; and the eunuch saw him no more, for he went on his way rejoicing." — Acts 8:39 (ASV)

When they were come up. So that Luke might finally conclude his account concerning the eunuch, he says that Philip was caught away from his sight. And that was of no small importance in confirming him, since he saw that that man was sent to him by God like an angel, and that he vanished before he could offer him any reward for all his efforts; from this he could gather that it was not for personal gain, since he vanished before he had been given even a penny.

Since Philip received no reward from the eunuch, let the servants of Christ learn from this to serve Him freely, or rather, let them serve people for nothing in such a way that they hope for a reward from heaven. Indeed, the Lord permits the ministers of the gospel to receive a reward from those they teach (1 Corinthians 9:9), but He also forbids them to be hirelings who labor for lucre’s sake (John 10:12–13). For this must be the goal at which they aim: to win the people themselves for God.

Rejoicing. Faith and the knowledge of God always naturally produce this fruit. For what truer source of joy can be conceived than when the Lord not only opens to us the treasures of His mercy, but pours out His heart into us (so to speak), and gives us Himself in His Son, so that we lack nothing for perfect felicity? The heavens then begin to look clear, and the earth begins to be quiet; the conscience, being delivered from the sorrowful and horrible feelings of God’s wrath, freed from the tyranny of Satan, and escaping from the darkness of death, beholds the light of life.

Therefore, it is a customary practice among the prophets to exhort us to be joyful and to triumph whenever they are about to speak of the kingdom of Christ. But because those people whose minds are possessed by the vain joys of the world cannot lift themselves up to this spiritual joy, let us learn to despise the world and all its vain delights, so that Christ may make us truly joyful.