וַיֹּ֕אמֶר לֹֽא־יֵרֵ֥ד בְּנִ֖י עִמָּכֶ֑ם כִּֽי־אָחִ֨יו מֵ֜ת וְה֧וּא לְבַדּ֣וֹ נִשְׁאָ֗ר וּקְרָאָ֤הוּ אָסוֹן֙ בַּדֶּ֙רֶךְ֙ אֲשֶׁ֣ר תֵּֽלְכוּ־בָ֔הּ וְהוֹרַדְתֶּ֧ם אֶת־שֵׂיבָתִ֛י בְּיָג֖וֹן שְׁאֽוֹלָה׃
Y él dijo: No descenderá mi hijo con vosotros; que su hermano es muerto, y él solo ha quedado: y si le aconteciere algún desastre en el camino por donde vais, haréis descender mis canas con dolor á la sepultura.
Rashi
לא ירד בני עמכם MY SON SHALL NOT GO DOWN WITH YOU — He did not accept Reuben’s offer. He said, “What a fool is this oldest son of mine! He suggests that I should kill his sons. Are they his only and not mine also?” (Genesis Rabbah 91:9)
Chizkuni
וקרהו אסון, “and some mishap would befall him;” the letter ו in the word קרהו has the vowel shuruk, whereas the letter ק has the semivowel sh’va.
Sforno
My son. Yaakov refers to Binyamin in this way because he was the only son left from his primary wife [Rochel].