1QS 3
Community RuleFor it is through the spirit of true counsel concerning the ways of man that all his sins shall be expiated, that he may contemplate the light of life. He shall be cleansed from all his sins by the spirit of holiness uniting him to His truth, and his iniquity shall be expiated by the spirit of uprightness and humility. And when his flesh is sprinkled with purifying water and sanctified by cleansing water, it shall be made clean by the humble submission of his soul to all the precepts of God. Let him then order his steps {to walk} perfectly in all the ways commanded by God concerning the times appointed for him, straying neither to the right nor to the left and transgressing none of His words, and he shall be accepted by virtue of a pleasing atonement before God and it shall be to him a Covenant of the everlasting Community.
Mark 1:4
2 As it is written in the prophet Isaiah, “Look, I am sending my messenger ahead of you, who will prepare your way, 3 the voice of one shouting in the wilderness, ‘Prepare the way for the Lord, make his paths straight.’” 4 In the wilderness John the baptizer began preaching a baptism of repentance for the forgiveness of sins. 5 People from the whole Judean countryside and all of Jerusalem were going out to him, and he was baptizing them in the Jordan River as they confessed their sins. 6 John wore a garment made of camel’s hair with a leather belt around his waist, and he ate locusts and wild honey.
Notes and References
"... With the discovery of the Scrolls, however, things began to change, and since 1948 many scholars have linked John directly or indirectly with the Qumran sect. The strong form of this claim - which this study shares - is that John started out as a member of the Qumran community. This is a controversial assertion, and it is based on circumstantial evidence, but there is a lot of that, including the following ... the water rites practiced by the Baptist and by the Qumran sect had a similar meaning, including their connection with repentance and forgiveness of sins (Mark 1:4; 1QS 3:4–12). Elsewhere in ancient Judaism, washing ceremonies were not connected with repentance and atonement but with the recovery of ritual purity ..."
Marcus, Joel John the Baptist in History and Theology (p. 28) The University of South Carolina Press, 2018