According to the custom of the priest’s office, his lot was to burn incense when he went into the temple of the Lord.
Berean Study Bible (BSB) - Luke 1:9 >he was chosen by lot, according to the custom of the priesthood, to enter the temple of the Lord and burn incense.
Textus Receptus (TR) - Luke 1:9 >κατὰ τὸ ἔθος τῆς ἱερατείας, ἔλαχε τοῦ θυμιᾶσαι εἰσελθὼν εἰς τὸν ναὸν τοῦ Κυρίου.