Unlike the Levites and others who turned to idols, the Levitical priests from Zadok's family stayed loyal to the Lord.
Zadok was the high priest during Solomon's time. His family was rewarded with access to the inner courtyard to perform important sacrifices closer to God.
These chapters often highlight that those who were faithful in the past would be rewarded with closer access to God and more privileges, while the unfaithful would remain farther away.