NET Bible
"he was chosen by lot, according to the custom of the priesthood, to enter the holy place of the Lord and burn incense."
— Luke 1:9, NET Bible
“According to the custom of the priest’s office, his lot was to burn incense when he went into the temple of the Lord.”
They were both righteous in the sight of God, following all the commandments and ordinances of the Lord blamelessly.
But they did not have a child, because Elizabeth was barren, and they were both very old.
Now while Zechariah was serving as priest before God when his division was on duty,
he was chosen by lot, according to the custom of the priesthood, to enter the holy place of the Lord and burn incense.
Now the whole crowd of people were praying outside at the hour of the incense offering.
An angel of the Lord, standing on the right side of the altar of incense, appeared to him.
And Zechariah, visibly shaken when he saw the angel, was seized with fear.