וַיִּשָּׂ֣א עֵינָ֗יו וַיַּ֞רְא אֶת־בִּנְיָמִ֣ין אָחִיו֮ בֶּן־אִמּוֹ֒ וַיֹּ֗אמֶר הֲזֶה֙ אֲחִיכֶ֣ם הַקָּטֹ֔ן אֲשֶׁ֥ר אֲמַרְתֶּ֖ם אֵלָ֑י וַיֹּאמַ֕ר אֱלֹהִ֥ים יָחְנְךָ֖ בְּנִֽי׃
約瑟舉目看見他同母的弟弟便雅憫，就說：«這就是你們對我說過的那個小弟弟嗎？»又說：«我兒，願上帝賜恩給你！»
Rashi
אלהים יחנך בני GOD BE GRACIOUS UNTO THEE, MY SON — With regard of the other sons of Jacob we have heard the expression “grace” used — viz., (33:5) “[The children] whom God hath graciously given (חנן) to thy servant”. But Benjamin had not then been born and therefore was not included amongst the children of whom Jacob used this term; on this account Joseph used the term “grace” in blessing him (Genesis Rabbah 92:5).
Radak
וישא עיניו, seeing that they all surrounded him without any specific order of seniority, Joseph looked up in order to recognise his brother Binyamin, [who had only been about 10 years old at the time he had last seen him. Ed.]
Sforno
Elokim be gracious. Since you are the only remaining son of your mother, as the brother’s had told him (see 44:20), may Hashem give you grace so that your brothers will feel affection towards you.