Answer
Zadok son of Ahitub was a Levite priest during the time of King David. For a long time, he was co-high priest with Abiathar. Zadok was a descendant of Aaron and a leader over his family of Levites (1 Chronicles 27:17).
When Absalom conspired against his father, David, David was forced to flee from Jerusalem (2 Samuel 15:13–14). Zadok and his son Ahimaaz, and his co-priest Abiathar and his son Jonathan accompanied David, with Zadok leading a procession of Levites who carried the ark of the covenant. As the people exited the city, Zadok’s Levites set down the ark, and Abiathar offered sacrifices (verse 24). Once the people had vacated Jerusalem, David ordered Zadok and Abiathar, along with their sons, to return with the ark to Jerusalem (verse 25). Zadok was to send word to David with any news of what was happening in the kingdom under Absalom.
David had also sent his friend Hushai back to Jerusalem to listen in on Absalom’s plans, and it was through him that Zadok and Abiathar heard that Absalom planned to seek out David and destroy him and the people who were with him. Hushai, Zadok, and Abiathar sent Ahimaaz and Jonathan to find David. After hiding in a well from Absalom’s men, Amimaaz and Jonathan were able to escape the city and bring the message to David: “Do not spend the night at the fords in the wilderness; cross over without fail, or the king and all the people with him will be swallowed up” (2 Samuel 17:16). David escaped, and it wasn’t much longer before David’s commander, Joab, killed Absalom (2 Samuel 18:1–15). Heartbroken at the death of his son, David returned to Jerusalem.
Years later, when King David was very old, his son Adonijah set himself up as king, even though David’s other son Solomon was to take the throne at David’s death (1 Kings 1:5). Adonijah had some supporters, including Abiathar the priest, but Zadok, Nathan the prophet, and several other important men supported David’s choice and opposed Adonijah (verse 8). Nathan told David’s wife Bathsheba what Adonijah was planning and advised her to apprise King David of the situation. She did so, and David ordered that Zadok and Nathan immediately take Solomon to Gihon and anoint him as king (verses 32–34).
When Zadok the priest anointed Solomon’s head with oil at Gihon, a trumpet was sounded, and all the people assembled began to shout and rejoice (1 Kings 1:39–40). The noise was so great that Adonijah, who was feasting nearby, heard it and wondered what was happening. At that moment, Abiathar’s son Jonathan arrived and told Adonijah that Solomon had been anointed king (verses 41–45). Adonijah fled to the temple and grabbed the horns of the altar, begging Solomon to spare his life (verses 50–51). Solomon did so, but Adonijah later renewed his designs on the throne, forcing Solomon to execute him (1 Kings 2:13–25).
Even though Abiathar had spurned King David’s wishes and supported Adonijah, Zadok stayed true to David and supported Solomon. Abiathar lost his priesthood as a result, but Zadok was rewarded with a position as one of Solomon’s chief officials (1 Kings 4:4) as well as being recognized as the sole high priest.
There are several other men named Zadok in the Bible, but they are only mentioned in one or two verses apiece. They can be found in 1 Chronicles 6:12 (Zadok the descendant of Zadok the priest), 1 Chronicles 9:11 and Nehemiah 11:11 (Zadok the Levite), 2 Kings 15:33 and 2 Chronicles 27:1 (Zadok the father of Jerusha), Nehemiah 3:4 (Zadok the son of Baana), Nehemiah 3:29 (Zadok the son of Immer), Nehemiah 10:21 (Zadok the Israelite leader), Nehemiah 13:13 (Zadok the scribe), and Matthew 1:14 (Zadok, an ancestor of Jesus Christ).