John Gill Commentary 2 Samuel 2:14

"And Abner said to Joab, Let the young men, I pray thee, arise and play before us. And Joab said, Let them arise." — 2 Samuel 2:14 (ASV)

And Abner said to Joab
Perceiving he made no motion towards an engagement with him, his orders from David being only to act on the defensive, and avoid as much as possible the effusion of blood:

let the young men now arise, and play before us ;
with their swords after the manner of gladiators or duellers; that it might appear who were best skilled in the use of the sword, and who were the bravest, stoutest, and most courageous; and this he proposed in a way of bravado, and in order to bring on a battle, or to decide the quarrel between them; and this bloody barbarous exercise Abner calls play, as if it was a diversion and pastime to see men wounding and killing one another:

and Joab said, let them arise ;
he accepted the challenge, not caring to be hectored and bullied by Abner.