TT #12 · Parashas Mikeitz · Passuk 42:8
וַיַּכֵּ֥ר יוֹסֵ֖ף אֶת־אֶחָ֑יו וְהֵ֖ם לֹ֥א הִכִּרֻֽהוּ׃
For though Joseph recognized his brothers, they did not recognize him.
Torah Temimah points to Yevamot 88a (and parallel discussions).
והם לא הכירוהו. א״ר חסדא, מלמד שיצא בלא חתימת זקן ובא בחתימת זקן.
English: “But they did not recognize him.” R’ Chisda said: This teaches that he left [Canaan] without a full beard and arrived [before them in Egypt] with a full beard.
On the daf / in context: The Gemara explains the asymmetry of recognition: Yosef recognized his brothers because they had already been bearded when he last saw them, while they failed to recognize him because he had matured into a bearded adult in the intervening years.
Type of Learning: Derash on the verse (Bavli sugya) — not a formal named middah of the 13; the sugya accounts for the narrative fact that recognition was one-sided.
What Is Learned: Yosef’s brothers did not recognize him because he had left them as a youth without a full beard and now stood before them as a mature, bearded Egyptian viceroy.