Only The Sons of Zadok May Perform the Full Priestly Functions (Ezekiel 44:15-31).
“But the priests, the Levites, the sons of Zadok, who kept the charge of my sanctuary when the children of Israel went astray from me, they will come near to me to minister to me. And they will stand before me to offer to me the fat and the blood,” says the Lord Yahweh. “And they will enter into my sanctuary, and they will come near to my table to minister to me, and they will keep my charge.”
One group of priests had clearly proved faithful to Yahweh through all the ups and downs of the history of the kings. Always there was a remnant who were faithful to Yahweh, that is one reason why Yahwism survived, humanly speaking. They were called ‘the sons of Zadok'. These had been faithful to the Davidic king from the first and in the time of the accession of the rightful heir had proved their loyalty and had been awarded the high priesthood (1 Kings 1:8; 1 Kings 1:32; 1Ki 1:38-39; 1 Kings 2:35. Compare 1 Chronicles 6:10 with Haggai 1:1; Haggai 1:15; 2 Chronicles 31:10). Zadok was descended from the line of Aaron (1 Chronicles 6:50-53). Now the ‘sons of Zadok' were to be rewarded by being awarded the sole right to ministry in the inner sanctuary. They alone would be able to offer the fat and the blood, they alone would minister at His table (compare Ezekiel 41:22).
‘The sons of Zadok' are probably not to be seen as totally limited to literal descendants of Zadok (not all such would necessarily have been faithful). Rather they were probably a band of faithful priests who had gathered under the banner of the Zadokite high priestly descendant and were differentiated because of their faithfulness to Yahweh, thus becoming a recognised band named ‘the sons of Zadok' (those who behave like Zadok - compare ‘the sons of Belial'). Many of them would no doubt be actual descendants, but not necessarily all.
But in the end the return of the exiles in the beginning was not as successful and triumphant as the prophets had hoped. It was one thing to look forward to a new beginning. It was another to hear the call ‘follow me' and participate in it. The temple was built after many stops and starts, and the Zadokite priesthood was established in the form of Joshua the High Priest (Haggai 1:12; Haggai 1:14; Zechariah 3:1-10. See also Nehemiah 11:11; 1 Chronicles 9:11). But the times were hard and strict rules were probably not adhered to. Adoption into ‘the sons of Zadok' of other priests would occur under the Zadokite leadership as long as they were ready to be true. The ancients did not stick to rigid differentiations like we do. They were more elastic, even when outwardly it appeared otherwise.
Further there was the problem of the returning exiles as against those who had remained in the land (who had not heard first hand the words of Ezekiel). Compromises would have to be reached in order for them to be able to worship together, and priests among them who proved worthy were no doubt also incorporated among ‘the sons of Zadok'. (We must remember again that ‘sons of' did not necessarily mean genealogical purity. It meant more ‘belonging to' or ‘behaving like', although no doubt genealogical purity was required for the High Priest himself). Thus it was not a theoretical ideal that was to be achieved, any more than the Mosaic ideal had ever been achieved. It was a practical one. Nor was it necessary to be particular as long as those who became part of ‘the sons of Zadok' were qualified as priests and faithful to their ministry. Soon any appointed by the high priest because of their faithfulness to Yahweh could be seen as being ‘sons of Zadok', for he stood in the place of Zadok. But there can be no question that the final authority in the temple did lie with the sons of Zadok, and did so until 171 BC when their high priest was removed for political reasons in the time of great apostasy. The Qumran community looked for the restoration of the sons of Zadok.