1 Chronicles 24:1-3

Young's Literal Translation

24 And to the sons of Aaron [are] their courses: sons of Aaron [are] Nadab, and Abihu, Eleazar, and Ithamar,

² and Nadab dieth, and Abihu, in the presence of their father, and they had no sons, and Eleazar and Ithamar act as priests.

³ And David distributeth them, and Zadok of the sons of Eleazar, and Ahimelech of the sons of Ithamar, according to their office in their service;