Rule Question

[KCref11]

My apologies if there is another thread I can put this under but I didnt see anything. Anyway, I pawed through the rule book and could not find anything on this scenario. Is it illegal for a player to yell at another player while he is shooting? I am talking about live action, not during a free throw. It wasnt even loud enough for either me or my partner to hear but I had a coach the other night telling me its illegal and I told him I was not aware of anything in the rulebook indicating it was illegal.

For some reason, the coach made this a very contentious conversation which resulted in a Technical foul later in the game because he couldnt let it go. I am really just looking for peace of mind.