And there appeared unto him an angel of the Lord standing on the right side of the altar of incense.
And there appeared unto him an angel of the Lord - not while at home, but in the act of discharging his sacerdotal duties; yet not when engaged outside at the altar of burnt offering, but during his week of inside-service, and so while alone with God. It is impossible not to observe here a minuteness of providential arrangement, proclaiming in every detail the hand of Him who as "wonderful in counsel and excellent in working."
Standing [the attitude of service], on the right side of the altar of incense - i:e., the south side, between the golden altar and the candlestick or lampstand; Zacharias being on the north side, and fronting the altar as he offered the incense. Why did the angel appear on the right side? Because, say some, the right was regarded as the favourable side [Schottgen, and Wetstein in Meyer]. See Matthew 25:33; and cf. Mark 16:5. But perhaps it was only to make the object more visible.