Of the many people named Eleazar whom the Old Testament mentions, the most important was Eleazar, the third of Aaron’s four sons (Num 3:2). When Aaron became high priest, his four sons became his priest-assistants (Exod 28:1-4). After the death of the two older sons (Lev 10:1-2), Eleazar and his younger brother Ithamar were given greater responsibility. Eleazar was in overall charge of the Levites (Num 3:32). Within the division of the Levites according to their three family groups, Eleazar seems to have had responsibility for the Kohath group (which had the higher duties; Num 4:15-16), and Ithamar had responsibility for the other two groups (Num 4:28,33).
God had prepared Eleazar to succeed Aaron as high priest (cf. Num 16:37; 19:3-4), and directed that Aaron, before he died, publicly appoint Eleazar to office (Num 20:23-28). Eleazar then assisted Moses as Aaron had previously (Num 26:63; 27:2; 31:12; 32:2). God directed that when Moses died, the new leader Joshua would not speak to God face to face as Moses had, but would receive God’s instructions through the high priest Eleazar (Num 27:18-23). God directed also that Joshua and Eleazar together were to be in charge of the work of dividing Canaan between Israel’s twelve tribes (Num 34:17; cf. Josh 17:4; 19:51; 21:1). (Concerning Eleazar’s famous son see PHINEHAS.)