John Gill Commentary 2 Samuel 11:19

"and he charged the messenger, saying, When thou hast made an end of telling all the things concerning the war unto the king," — 2 Samuel 11:19 (ASV)

And charged the messenger
Gave him a particular direction and instruction what he should say at the close of his narrative, according as he should observe the king's countenance to be:

saying, when you have made an end of telling the matters of the war
to the king ;
giving an account of all the events that happened since the siege was begun to that time.