ולא יכלו דברו לשלום. מתוך גנותם למדנו שבחם, שלא דברו אחת בפה ואחת בלב
רש”י וישב לז ד
This would seem to contradict the way R Avigdor Miller is quoted, Rashi says once they hated Yosef which was admittedly a Gnus, it was then a Shvach that they at least didn’t act falsely.
Rashi’s mekor is a medrash there (BR 84:9) which contrasts the Shvotim to Avsholom who was capable of acting differently to how he really felt (Maharzav). The Matnos Kehuna calls this geneivas daas; the Yefei Toar calls it chanufa.
Do you have a source/further information about this quote