(Ezekiel also distinguishes between altar-priests and lower Levites, but in Ezekiel the altar-priests are sons of Zadok instead of sons of Aaron; many scholars see this as a remnant of struggles between different priestly factions in First Temple times, finding resolution by the Second Temple into a hierarchy of Aaronite altar-priests and lower-level Levites, including singers, gatekeepers and the like).In chapter 10, God kills Nadab and Abihu, the oldest sons of Aaron, for offering "strange incense".