In the synagogue the Torah is read aloud in a fixed annual cycle of fifty-four weekly portions (parashiyot), one each Shabbat morning, with certain adjacent portions doubled in ordinary years so the sequence fits the calendar. Each portion is named for a distinctive word near its opening and is paired with a haftarah, a reading from the Prophets. The cycle closes and restarts on Simchat Torah. Tzav ('Command', Leviticus 6:1-8:36) continues the sacrificial law from the priests' perspective, the tending of the altar fire, the portions of the priests, and describes the seven-day consecration of Aaron and his sons to the priesthood.
Tzav's instruction that the fire on the altar 'shall be kept burning, it shall not go out' (Leviticus 6:13) is read by rabbinic commentary as establishing a continuous, uninterrupted flame maintained by the priesthood, later tradition holding that this perpetual fire persisted throughout the First and Second Temple periods and became a model, in later synagogue architecture, for the ner tamid, the eternal light kept burning before the ark in synagogues to this day. The consecration of Aaron and his sons across a full seven days, during which they were confined to the sanctuary entrance and repeated the ordination rites daily (Leviticus 8:33-35), is read by commentators as establishing the pattern, echoed in later Jewish law's seven-day periods for other transitions including mourning, of a full week as the span necessary for a significant change in status to be fully effected.