Sforno on Genesis 37:4/ספורנו על בראשית ל״ז:ד׳

1ויראו אחיו כי אותו אהב אביהם, here Yaakov had committed an error, allowing the love in his heart for Joseph to be now become visible through preferential treatment of him.

2ולא יכלו דברו לשלום, even though the brothers had to speak to Joseph pertaining to their business dealings both concerning household problems and problems with the herds and flocks, something imposed upon them by their father’s command to see in him their manager, they did not speak to him concerning any private matters, brotherly concerns.