Rabbeinu Bahya
ויפלו לפניו ארצה, “they fell to the ground before him (Joseph).” All ten brothers fell to the ground plus Binyamin. This was the realisation of Joseph’s dream in which eleven stars bowed down to him (37,9).
Rav Hirsch on Torah
Nun tritt Juda hervor; denn nun gilt es, seine Bürgschaft zu lösen.