How could Yosef be so readily prepared to go to his brothers, knowing how much they hated him?
How could Yakov send Yosef to his brothers, knowing how much they hated him?
Moshav Zekenim (14), Rosh (15), Hadar Zekenim: Yakov thought that it is a Safek if the brothers will harm him, but if the brothers delay in Shechem, Nochrim will Vadai kill them to avenge the destruction of Shechem. It is better to tell the brothers to return, even though there is risk to Yosef. 1
Hashem caused Yakov to do so. Refer to 37:14:2:1*.
Moshav Zekenim, Rosh: The brothers would believe only Yosef - if their father sent his favorite son (surely he was adamant that they leave).
רש"י: לשון ענוה וזריזות: אולי זה רק לשון עניה על שאלה?