Luke 1:9

“According to the custom of the priest's office, etc.] In which, every man took his part in the execution of it by lot; and which was not an original settled law of God; but a custom, which, in process of time, through the number of the priests, took place, and prevailed: the occasion of it was this; “at first, whoever would, might sweep the altar, or cleanse it — — it happened that two alike ran, and came up to the ascent of the altar, and one thrust down the other, and he fell, and his leg was broke; and when the sanhedrim saw that they came into danger, they ordered that they should not cleanse the altar, but by lot f28.” And so likewise all other sorts of service were settled by lot: his…”

“his lot was to burn incense--The part assigned to each priest in his week of service was decided by lot. Three were employed at the offering of incense--to remove the ashes of the former service; to bring in and place on the golden altar the pan filled with hot burning coals taken from the altar of burnt offering; and to sprinkle the incense on the hot coals; and, while the smoke of it ascended, to make intercession for the people. This was the most distinguished part of the service (Rev 8:3), and this was what fell to the lot of Zacharias at this time [LIGHTFOOT].”

“According to the custom of the priest’s office, his lot was. - The Jewish writers inform us that it was customary for the priests to divide their daily task by “lot.” To burn incense - Incense is an aromatic or white rosin procured from trees, chiefly in Arabia. It is obtained by making incisions in the tree, and the gum flows out. It is distinguished for an especially pleasant “smell” when burned, and was therefore used in ancient worship. It was burned by the priest twice a day Exodus 30:7, and it seems to have been emblematic of prayer and praise, or of the grateful offerings of the heart wafted toward heaven. The incense used in the temple was made of stacte, onycha, and galbanum Exodus…”

“his: Exo 30:7, Exo 30:8, Exo 37:25-29; Num 16:40; Sa1 2:28; Ch1 6:49, Ch1 23:13; Ch2 26:16; Ch2 29:11; Heb 9:6 Luke 1:10”