Luke 1:9

Luke 1:9. According to the custom of the priesthood. To be joined with what follows, not with what precedes. The ‘custom' was to assign by lot for each day the various parts of the service to the priests of the course on duty for the week. The most honorable office, which fell to Zacharias on this occasion, was allotted to the same person but once, i.e., for one day during the week of service.

To enter into the temple of the Lord, i.e., ‘the holy place.' Beyond this only the high-priest could go.

And burn incense. At the time of the morning and of the evening sacrifice. The sacrifice was offered on the great altar of burnt - offering, which stood outside in the court of the priests. One priest took fire from this altar to the altar of incense, and then left the priest, whose duty it was to bum incense, alone in the holy place; the latter (Zacharias in this case), at a signal from the priest presiding at the sacrifice, kindled the incense.