וְיַעֲקֹ֣ב שָׁמַ֗ע כִּ֤י טִמֵּא֙ אֶת־דִּינָ֣ה בִתּ֔וֹ וּבָנָ֛יו הָי֥וּ אֶת־מִקְנֵ֖הוּ בַּשָּׂדֶ֑ה וְהֶחֱרִ֥שׁ יַעֲקֹ֖ב עַד־בֹּאָֽם׃
און יעקב האָט געהערט אַז ער האָט פֿאַראומרײניקט זײַן טאָכטער דינהן, װען זײַנע זין זײַנען געװען מיט זײַן פֿי אין פֿעלד; האָט יעקב געשװיגן ביז זײ זײַנען געקומען.
Sforno
והחריש יעקב עד בואם, he refrained from starting a quarrel until his sons would have been informed of what happened so that they could be on their guard against their adversaries.
Or HaChaim
עד בואם, until they came home. Jacob sent a message to them asking them to return home.
Radak
ויעקב שמע כי טמא, Shechem, who had already been mentioned (hence his name does not need to be repeated here and a pronoun will do) and that as a result of what he did, Dinah had been defiled by an uncircumcised person who had been intimate with her.