I will help you bring all Israel over to you.

2 Samuel 3:2-21
 Six Sons were born to David in Hebron.
Then Abner sent messengers on his behalf to say to David, “Whose land is it? Make an agreement with me, and I will help you bring all Israel over to you.”
“Good,” said David. “I will make an agreement with you. But I demand one thing of you: Do not come into my presence unless you bring Michal daughter of Saul when you come to see me.” 
Abner conferred with the elders of Israel and said, “For some time you have wanted to make David your king.
Abner also spoke to the Benjamites in person. Then he went to Hebron to tell David everything that Israel and the whole tribe of Benjamin wanted to do.
Ishbosheth is not the man his father was. Abner is real power. If he transfers his support to David, he carries the nation with him. 
Why?
Because Abner slept with Saul's a concubine named Rizpah the daughter of Aiah, so Abner wanted to help David build kingdom which is God promised to David.
Abner wanted to get more profit from David for he may help David, he has the real power of Israel.
Ishbosheth has not any choice for he is not Saul. 
David was living peace in Hebron, so he has six sons.
David loved Michal, his wife. So he asked Abner bring Michal back to him
大衛要求歸還米甲，一方是大衛最愛的女人，再則是掃羅的女兒，比較有名份，接掃羅的位子。
押尼珥倒向大衛，伊施波設也聽從大衛，神將這三人轉向大衛，減少內戰的持續，造成更多生命財產的損失。這是神的作為，回應大衛常常求問神。不用武力、刀槍取得王位。
How?
There is not real love among people. Pray to the Lord for anything! 凡事求問神。