1 Kings 1:7
ESV
He conferred with Joab the son of Zeruiah and with Abiathar the priest. And they followed Adonijah and helped him.
NIV
Adonijah conferred with Joab son of Zeruiah and with Abiathar the priest, and they gave him their support.
NASB
Now he had conferred with Joab the son of Zeruiah and with Abiathar the priest; and they allied themselves with Adonijah.
CSB
He conspired with Joab son of Zeruiah and with the priest Abiathar. They supported Adonijah,
NLT
Adonijah took Joab son of Zeruiah and Abiathar the priest into his confidence, and they agreed to help him become king.
KJV
And he conferred with Joab the son of Zeruiah, and with Abiathar the priest: and they following Adonijah helped him.
NKJV
Then he conferred with Joab the son of Zeruiah and with Abiathar the priest, and they followed and helped Adonijah.
What does 1 Kings 1:7 mean?
Adonijah is following in the footsteps of his older brother Absalom. He's assembled chariots, horsemen, fifty men to guard him, and his father's officers. This is an attempt to steal the crown (2 Samuel 15:1–12). Unlike Absalom, he's waited until David is too frail to fight back (1 Kings 1:1–4).Absalom enticed men from outside Jerusalem and David's best counselor, Ahithophel. Adonijah has the loyalties of Joab and Abiathar.
Joab is David's nephew and the commander of his army. On the surface, his switch is curious. He has fought with David since David fled Saul (1 Samuel 22:1–2; 26:6). He's the only non-prophet in David's life bold enough to confront the king's questionable decisions (2 Samuel 14:1–3; 18:5, 14–15; 19:1–8). He remained loyal to David when Absalom ran his father out of Jerusalem (2 Samuel 18:1–2). Israel is secure from enemies largely because of Joab (2 Samuel 12:26–28; 1 Kings 11:15–16).
But Joab is also a murderer. First, he murdered Saul's general Abner after Abner had made a treaty with David (2 Samuel 3:22–30). Then, when David fired Joab for killing Absalom and put Amasa in his place, Joab slaughtered Amasa (2 Samuel 20:4–13). Considering their relationship, Joab likely knows David wants Solomon to be king. He's probably savvy enough to suspect that David will tell Solomon to execute him (1 Kings 2:5–6). Making Adonijah king is his hope for survival.
Abiathar's switch is less clear. He's the priest, descended from Eli. He has faithfully served God his whole life, and he's been with David since King Saul murdered his father and the other priests at Nob (1 Samuel 22).
Even so, he is vulnerable. Eli was the priest when Samuel was a boy. Because Eli allowed his sons to sin in the context of their priestly duties, God vowed to remove Eli's line from the position of priest (1 Samuel 2:27–36). It's possible Abiathar is afraid Solomon will follow God enough to remove him as priest and install Zadok, instead. Solomon does, but not because of Eli's curse; he does so because Abiathar betrays his father (1 Kings 2:26–27).