Tanach · Rishonim on Tanach · Ramban · Torah
Ramban on Genesis 18:11/רמב"ן על בראשית י״ח:י״א
אבָּאִים בַּיָּמִים הָאָדָם בִּימֵי בְּחוּרוֹתָיו יִקָּרֵא "עוֹמֵד בַּיָּמִים", וְיִקָּרְאוּ "יָמָיו", כִּי הֵם שֶׁלּוֹ, כִּלְשׁוֹן "אֶת מִסְפַּר יָמֶיךָ אֲמַלֵּא" (שמות כג כו), אֲבָל כַּאֲשֶׁר יַזְקִין וְיִחְיֶה יָמִים רַבִּים מֵרֹב בְּנֵי הָאָדָם בְּדוֹרוֹ, יִקָּרֵא "בָּא בַּיָּמִים", מִפְּנֵי שֶׁהוּא כְּבָא בְּאֶרֶץ אַחֶרֶת נוֹסֵעַ מֵעִיר וּבָא אֶל עִיר מִיּוֹם אֶל יוֹם:
1‘BA’IM BAYAMIM’ (ADVANCED IN DAYS). In his youthful days a man is called “standing in days,” and they are referred to as “his days” because they belong to him, just as in verse The number of thy days will I fulfill.97 But when he gets old and has lived longer than most people of his generation, it is said of him that he is ba bayamim, [literally, “came into days”], because it is as if he came into another land, travelling from and arriving in a city each and every day.
בחָדַל לִהְיוֹת לְשָׂרָה אֹרַח כַּנָּשִׁים הוּא הַזְּמַן לְהֵרָיוֹן, כִּי אַחֲרֵי הֶפְסֵק הָאֹרַח מֵחֲמַת זִקְנָה לֹא תֶּהֱרֶינָה:
2IT HAD CEASED TO BE WITH SARAH AFTER THE MANNER OF WOMEN. This is the time of pregnancy, for after menstruation has ceased due to old age, a woman will not become pregnant.