The roles and responsibilities of the priests and Levites are foundational to the religious and communal life of ancient Israel, as outlined in the Old Testament. These duties are primarily detailed in the books of Exodus, Leviticus, Numbers, and Deuteronomy, where God establishes a covenant with the Israelites and sets apart the tribe of Levi for special service.

Priests:

The priests, specifically from the line of Aaron, were entrusted with the sacred duty of serving in the Tabernacle and later in the Temple. Their primary responsibilities included offering sacrifices, maintaining the sanctity of the sanctuary, and acting as mediators between God and the people.

1. Offering Sacrifices: The priests were responsible for performing the various sacrifices and offerings prescribed in the Law. This included burnt offerings, sin offerings, and peace offerings, among others. Leviticus 1-7 provides detailed instructions on how these sacrifices were to be conducted.

2. Maintaining the Sanctuary: The priests were charged with the care and maintenance of the Tabernacle and its furnishings. This included ensuring that the lamps were kept burning, the bread of the Presence was regularly replaced, and the altar of incense was tended to. Exodus 27:20-21 states, "And you are to command the Israelites to bring you pure oil of pressed olives for the light, to keep the lamps burning continually."

3. Teaching the Law: Priests were also tasked with teaching the Israelites God's statutes and laws. They served as judges in certain disputes and were responsible for instructing the people in matters of ritual purity and holiness (Leviticus 10:11).

4. Blessing the People: The priests were given the authority to bless the people in the name of the Lord. Numbers 6:23-27 records the priestly blessing: "The LORD bless you and keep you; the LORD make His face shine upon you and be gracious to you; the LORD lift up His countenance upon you and give you peace."

Levites:

The Levites, while not all serving as priests, played a crucial role in supporting the priestly ministry and the broader religious life of Israel. They were set apart for service to assist the priests and to perform various duties related to the Tabernacle and Temple.

1. Assisting the Priests: The Levites were responsible for assisting the priests in their duties, including the preparation and handling of sacrifices and offerings. Numbers 3:6-9 outlines their role in supporting Aaron and his sons.

2. Guarding the Tabernacle: The Levites were charged with the protection and transportation of the Tabernacle and its sacred objects during the Israelites' wilderness journeys. Numbers 1:50 states, "Instead, appoint the Levites over the Tabernacle of the Testimony, along with all its furnishings and everything belonging to it."

3. Singing and Music: In the Temple period, the Levites were also involved in the musical aspect of worship, providing songs and instrumental music during the services. 1 Chronicles 15:16 mentions David's command to appoint Levites as musicians.

4. Teaching and Judging: Some Levites were also involved in teaching the Law and serving as judges, similar to the priests. They played a role in educating the people and ensuring adherence to God's commandments (Deuteronomy 33:10).

The division of labor between the priests and Levites ensured that the worship and religious practices of Israel were conducted in accordance with God's commands, maintaining the holiness and order required for the community's covenant relationship with Him.