'Custom' in the Bible

as was the custom of the priesthood, he was chosen by lot to enter [the sanctuary of] the temple of the Lord and burn incense [on the altar of incense].

And when He was twelve years old, they went up to Jerusalem, according to the custom of the Feast;

So He came to Nazareth, where He had been brought up; and as was His custom, He entered the synagogue on the Sabbath, and stood up to read.