The role of the priest in ancient Israel was integral to the spiritual and communal life of the nation. Priests were primarily from the tribe of Levi, specifically the descendants of Aaron, and were set apart for sacred duties. Their responsibilities were multifaceted, encompassing religious, educational, and judicial functions.

1. Offering Sacrifices:
One of the primary duties of the priests was to offer sacrifices on behalf of the people. This included burnt offerings, grain offerings, peace offerings, sin offerings, and guilt offerings. The Book of Leviticus provides detailed instructions on how these sacrifices were to be conducted. Leviticus 1:9 states, "The priest is to burn all of it on the altar as a burnt offering, an offering made by fire, a pleasing aroma to the LORD."

2. Maintaining the Tabernacle/Temple:
Priests were responsible for the upkeep and service of the Tabernacle, and later the Temple. This included ensuring that the sacred space was kept holy and that all rituals were performed according to divine instructions. Numbers 18:5 emphasizes this duty: "You are to perform the duties of the sanctuary and of the altar, so that wrath will not fall on the Israelites again."

3. Teaching the Law:
Priests were also tasked with teaching the Israelites the Law of God. They served as instructors and interpreters of the Torah, guiding the people in understanding and applying God’s commandments. Malachi 2:7 highlights this role: "For the lips of a priest should preserve knowledge, and people should seek instruction from his mouth, because he is the messenger of the LORD of Hosts."

4. Mediating Between God and Man:
As mediators, priests represented the people before God and God before the people. They interceded on behalf of the Israelites, offering prayers and sacrifices to atone for the sins of the nation. Hebrews 5:1 reflects this mediatory role: "Every high priest is appointed from among men to represent them in matters relating to God, to offer gifts and sacrifices for sins."

5. Conducting Ritual Purifications:
Priests were responsible for performing rituals of purification, which were necessary for maintaining the holiness of the community. This included diagnosing and cleansing leprosy, as well as purifying those who had become ceremonially unclean. Leviticus 14:11 describes this process: "The priest who performs the cleansing shall present the man to be cleansed, along with these offerings, before the LORD at the entrance to the Tent of Meeting."

6. Blessing the People:
The priests were also charged with blessing the people in the name of the Lord. The Aaronic Blessing, found in Numbers 6:24-26, is a well-known example: "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."

7. Judicial Responsibilities:
In addition to their religious duties, priests often served as judges in legal matters, particularly those involving religious law. Deuteronomy 17:9 instructs, "Go to the Levitical priests and to the judge who is in office at that time. Inquire of them, and they will give you the verdict."

The duties of the priests were essential for maintaining the covenant relationship between God and Israel. Their service ensured that the people could approach God in holiness and receive His blessings.