Then an angel of the Lord appeared to him, standing on the right side of the altar of incense. – Luke 1:11

How peculiarly favoured Zacharias was! An angel of the Lord appeared unto him. Not to any of the other priests, when they were offering incense, did such a heavenly visitor come. And what welcome tidings he brought! It was a wonderful message that he was to be the father of a child great in the sight of the Lord, one who should minister in the spirit and power of Elias, and become the forerunner of the Messiah. This surely was a signal instance of Divine favour. And mark this, beloved, our God is very jealous of those whom He highly favours. You cannot have privileged communications from the Lord, or be admitted into close communion with Him, without finding that He is a jealous God. The nearer we draw to Him, the more hallowed our sense of His presence will be. But to doubt His Word, or question the fulfillment of His promise when He speaks kindly to us, must incur His censure. I speak after the manner of men; we do not expect from a stranger the esteem which we ought to merit from our servants. But our friends, who know us better than servants, ought to trust us more implicitly. And yet beyond common friendship in the near relation and tender attachment of a wife to her husband, the most unqualified confidence should be reposed. Even so, my brethren, if you and I have ever been permitted to lean our heads on Jesus’ bosom; if we have sat down at His banquets, and His banner over us has been love; if we have been separated from the world by peculiar fellowship with Christ, and have had choice promises given us, we cannot, like Zacharias, ask, “Whereby shall I know” without grieving the Holy Spirit of God, and bringing upon ourselves some sad chastisement as the result.~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/3495.cfm