Background:
Abner, the son of Ner, was the commander of Saul's army and a significant figure in the early monarchy of Israel. After Saul's death, Abner initially supported Ish-bosheth, Saul's son, as king over Israel, while David was anointed king over Judah. The ensuing conflict between the house of Saul and the house of David set the stage for Abner's proposal to David.

Biblical Account:
The account of Abner's proposal to David is found in 2 Samuel 3. The narrative describes a period of prolonged conflict between the house of Saul and the house of David, during which David grew stronger while the house of Saul grew weaker.

Abner's Defection:
Tensions arose between Abner and Ish-bosheth when Ish-bosheth accused Abner of sleeping with Saul's concubine, Rizpah. This accusation angered Abner, who felt his loyalty and contributions to the house of Saul were being undermined. In response, Abner decided to shift his allegiance to David, recognizing that God had promised the kingdom to David.

Proposal to David:
Abner sent messengers to David, proposing an alliance and offering to bring all Israel under David's rule. Abner's message to David was, "Make your covenant with me, and behold, my hand shall be with you to bring all Israel over to you" (2 Samuel 3:12). David agreed to the proposal but stipulated that Abner must bring Michal, Saul's daughter and David's former wife, when he came to see him.

Meeting with David:
Abner complied with David's condition and arranged for Michal's return. He then met with the elders of Israel, persuading them to support David as king, reminding them of God's promise to deliver Israel through David. Abner also spoke directly to the Benjamites, Saul's own tribe, to secure their support.

Abner then went to Hebron to meet David, accompanied by twenty men. David hosted a feast for Abner and his men, signaling the acceptance of Abner's proposal. Abner assured David, "I will arise and go, and will gather all Israel to my lord the king, that they may make a covenant with you, and that you may reign over all that your heart desires" (2 Samuel 3:21). David sent Abner away in peace, marking a pivotal moment in the unification of the kingdom.

Aftermath:
Despite the promising alliance, Abner's efforts were cut short. Joab, the commander of David's army, harbored a personal vendetta against Abner for killing his brother Asahel in battle. Unbeknownst to David, Joab lured Abner back to Hebron and killed him in revenge. David mourned Abner's death and distanced himself from the act, declaring his innocence and cursing Joab's house.

Significance:
Abner's proposal to David was a crucial turning point in the establishment of David's rule over a united Israel. It demonstrated the shifting political landscape and the fulfillment of God's promise to David. Despite Abner's untimely death, his actions paved the way for the eventual unification of the tribes under David's kingship.