שבעה דברים בחכם וכו' -- אבות דרבי נתן

See Avot D'Rebbi Natan on that Mishna (Perek ??):

אינו נכנם לתוך דברי חבירו -- Usually this is understood from a prudent point of view i.e. let a person finish their words before you assume you know what they are going to say, you may be wrong.
... I'd like to suggest differently. See the proof the אבות דרבי נתן brings is from Hashem's allowing Avraham to go through the whole "bargaining the # of Tzadikim" in Sdom and the other 4 cities.
...if so, it's not an issue of prudence on the part of the chacham...

Rather, Hashem knew there weren't even 10 Tzadikim but he went through the whole drawn out process with Avraham for Avraham i.e. Avraham needs to be allowed to finish his thought process and work through his misperceptions and mistakes himself. He needs to be allowed to "work it out himself, for himself" and even if Hashem Himself is the Chacham on the other side, knowing his friend is completely off the mark, restraint and patience has to be given to allow the other party to realize the truth themselves. The objective "Right and Wrong" of the matter is irrelevant vis-a-vis the individual who has yet to discover the truth for himself.