Albert Barnes Commentary 2 Samuel 3:14

"And David sent messengers to Ish-bosheth, Saul`s son, saying, Deliver me my wife Michal, whom I betrothed to me for a hundred foreskins of the Philistines." — 2 Samuel 3:14 (ASV)

Sent messengers to Ish-bosheth - This was not sent to Abner, because the alliance between David and Abner was a profound secret. Instead, the message was for Ish-bosheth, who David knew must act, weak as he was, according to Abner’s dictation. Abner’s first open act of allegiance to David was thus done at Ish-bosheth’s command. The effect of the humiliation placed upon Ish-bosheth—exposing his weakness to his own subjects and thereby shaking their allegiance to him—was so great that Abner no longer needed to use any disguise.