(See the "The New Priests And Their Garments" section of the Chapter Comments for an introduction to this chapter.)
“And bring near to yourself Aaron your brother, and his sons with him, from among the children of Israel, that he may minister to me in the priest's office, even Aaron, Nadab and Abihu, Eleazar and Ithamar, Aaron's sons.”
The choice was wise. Moses was unavailable, for he had a nation to lead through the wilderness and could not give his time to the office of ‘the Priest'. He would always be unique. He was Yahweh's man. But Aaron was equally recognised by the people as having been an instrument of God, and his relationship to Moses, and his part in the deliverance, were equally recognised. Indeed in an age when the firstborn was often seen as pre-eminent it might have been seen as appropriate that the elder brother be appointed.
That Aaron as ‘the Priest' was seen as holding a priesthood superior to that of his sons comes out in the special garments which he was to wear. He was the leading priest, called ‘the Priest', a position described as the ‘great priest' when differentiation needed to be made and no name could be given because the reference was general (Leviticus 21:10; Numbers 35:25).
His sons acted as his assistants. Nadab and Abihu had been with him when they had feasted before God in the Mount (Exodus 24:1), but would die (possibly struck by lightning) because they offered ‘strange fire' (with incense - compare Exodus 30:9) before Yahweh, in disobedience to His commands (Leviticus 10:1-2). We know little of the future of Ithamar (see 38:21; Numbers 4:28; Numbers 4:33), but Eleazar would later become ‘the Priest' (Numbers 20:25-26; Numbers 26:3; Numbers 26:63; Numbers 34:17; Joshua 14:1), and from him would be descended Zadok (1 Chronicles 6:8).
Much later the descendants of Ithamar would be ‘the Priest' although we do not know how it came about. It was possibly because a vacancy was left when there was no adult son of the line of Eleazar. Eli, Ahimelech and Abiathar were all descended from Ithamar (compare 1 Chronicles 24:3; 1 Samuel 22:20; 1 Kings 2:27), but with Zadok the Priesthood returned to the house of Eleazar.
Thus five were appointed, the covenant number, of whom three would die because of disobedience (Numbers 20:24; Leviticus 10:1-2), and one would simply fade from the scene (but see Exodus 38:21; Numbers 4:28; Numbers 4:33). When God chooses a man he must show himself worthy. Presumption may lead to his downfall.
It is significant that the four sons are divided into two sets of ‘two', that is, two sets of witnesses. The first two failed in their witness. The second two carried it on. None, except Eliezer, was ever titled ‘the Priest', but he appears to have taken over the role before Aaron's death, possibly because of Aaron's great age (Numbers 16:39; Numbers 19:3-4), after which he only is called ‘the Priest' (e.g. Numbers 26:1 and regularly), apart from a mention of Aaron in the designation of Eliezer as ‘son of Aaron the priest'. See also Leviticus 6:22; Deuteronomy 10:6 for the idea of a sole ‘Priest'. The plural ‘priests' can be applied to Aaron's sons but not even then as a specific title (Numbers 3:3; Numbers 10:8). All are called ‘son(s) of Aaron, the priest'.
In Leviticus ‘the priest' is spoken of generally, either as himself acting, or as possibly acting through his assistants (see Leviticus 6:22 which emphasises this position). Later descendants called ‘the Priest' are Phinehas (Joshua 22:30 - when Eliezer has grown old), Eli (1 Samuel 1:9; 1 Samuel 2:11), Ahimelech (1 Samuel 21:1; 1 Samuel 21:2; 1 Samuel 2:11), Abiathar (1 Samuel 23:9; 1 Samuel 30:7 and often). Zadok is also called ‘the Priest' (2 Samuel 15:27; 1 Kings 1 (eight times); 2:35; 4:2; 1 Chronicles 16:39 (in contrast with ‘his brethren the priests') 1 Chronicles 24:6) even when Abiathar is still alive, and they are then coupled together as ‘the priests' (2 Samuel 15:35; 2 Samuel 17:15; 2 Samuel 19:11). This may well be because when Abiathar deserted to David (1 Samuel 23:9; 1 Samuel 30:7), Saul appointed Zadok in his place. The tension between them was resolved when Abiathar supported Adonijah and Zadok supported Solomon (1 Kings 1), resulting in Abiathar's downfall.
The responsibilities of the priests in general in Israel were fourfold.
1). They had the responsibility of maintaining the service of the Holy Place. This included burning the incense each morning and evening, trimming and refilling the lamps each evening, and replacing the showbread each Sabbath day.
2). They maintained the service of the courtyard of the Dwellingplace.. This included the offering of sacrifices each morning and evening, and as required, and blessing the congregation after the daily sacrifice. It also meant keeping the fire on the brazen altar burning always for when sacrifices were brought to be offered, and periodically removing its ashes.
3). They were responsible to inspect and appraise people and their sacrifices. These included lepers coming for examination, wives accused of adultery, and things offered to God or dedicated to the sanctuary.
4). Finally, they were to teach and counsel the people. It was their responsibility to communicate the Law of Moses to the congregation and to pronounce on difficult cases of law.
“ The Priest” had the additional responsibility of overall supervision, responsibility to ensure that the ordinances were correctly carried out, responsibility for the use of the Urim and Thummim and especially responsibility for officiating solely in unique situations like the Day of Atonement when he, and he alone, entered the Most Holy Place, the Holy of Holies.
The word used for ‘priest' is ‘cohen', which more rarely signified a mediator, a chief representative when it was also used of chief representatives of a king (see 2 Samuel 8:18; 2 Samuel 20:26; 1 Kings 4:5). But the ‘priest' was mainly the representative of Yahweh and the mediator between man and his God.