וְכִלְכַּלְתִּ֤י אֹֽתְךָ֙ שָׁ֔ם כִּי־ע֛וֹד חָמֵ֥שׁ שָׁנִ֖ים רָעָ֑ב פֶּן־תִּוָּרֵ֛שׁ אַתָּ֥ה וּבֵֽיתְךָ֖ וְכָל־אֲשֶׁר־לָֽךְ׃
흉년이 아직 다섯 해가 있으니 내가 거기서 아버지를 봉양하리이다 아버지와 아버지의 가속과 아버지의 모든 소속이 결핍할까 하나이다 하더라 하소서
Ibn Ezra
For he was a son of old age. As it sounds, for he begat him when he was 91. His brother Binyamin they also called "child of old age." And after these two none were born to him.
Rabbeinu Bahya
Rabbi Yoseph in Tossephta Sotah 10,9 points out that the famine resumed after Yaakov’s death and that Joseph’s promise to provide for his brothers (50,21 made after his father had died) was precisely because the famine had resumed at that time. Just as Joseph had used the expression וכלכלתי אתכם, “I will provide for you” in 45,11 at a time when the famine was in full force, so the same expression used in chapter 50 also reflects that the famine was again in full force. Rabbi Shimon did not feel that such an explanation would reflect credit on G’d as it creates the impression that blessings by the righteous are valid only during their own lifetime. His son Rabbi Eleazar nevertheless said that he preferred Rabbi Yoseph’s interpretation to that of his father.