Luke 2:17

Verse 17. When they had seen it. When they had satisfied themselves of the truth of the coming of the Messiah, and had ascertained that they could not have been mistaken in the appearance of the angels. There was evidence enough to satisfy them that what the angels said was true, or they would not have gone to Bethlehem. Having seen the child themselves, they had now evidence that would satisfy others; and accordingly they became the first preachers of the gospel, and went and proclaimed to others that the Messiah had come. One of the first duties of those who are newly converted to God, and a duty in which they delight, is to proclaim to others what they have seen and felt.