Hi,
this story shows the sublime and the beautiful character of our Prophet صلى الله عليه و سلم that he was served by Anas رضي الله عنه for 10 years and when he would do a mistake, i.e. not do an act that he was told to be done or the act which he did which he was not supposed to do, Prophet صلى الله عليه و سلم never asked him the reason why he didn't do that act since he صلى الله عليه و سلم said (not mentioned in the narration above), "Whatever was to come will come and whatever is not going to happen will not happen." Meaning he صلى الله عليه و سلم had reliance (Tawakkul in Arabic) in Allah سبحانه و تعالىthat whatever would happen would be good and Allah سبحانه و تعلى knows best.
I know it's a bit complicated. If you have any other questions, please do ask.