What is the meaning of "Ba'im ba'Yamim"?
Ramban: In a person's youth, his days belong to him - they are called "Yamav," and he is referred to as 'Omeid ba'Yamim.' However, when he becomes old and his age exceeds that of his contemporaries, he is called a 'Ba ba'Yamim' - like a man who enters a land that does not belong to him, as he travels from place to place, one day after the other.
What does it mean that Sarah ceased having "Orach ka'Nashim"?
Rashi: She ceased having Orach Nidus (a menstrual cycle). 1
Da'as Zekenim, Rosh and Riva ask that above, Rashi (to 18:8) said that Sarah became a Nidah! Rather, Rashi means that she did not have menopause (she did not cease to have menstrual cycles in her old age). Alternatively, she returned to see after menopause, unlike others. R. Elyakim explains Rashi simply; she ceased becoming a Nidah, and only today it returned to her. Even so, she laughed, for she did not consider this a sign that she could give birth - refer to 18:8:1:1*. See also Keli Yakar.
QUESTIONS ON RASHI
Rashi writes: "'The way of women' - i.e. the way if menstruation." Why does Rashi add this?
Gur Aryeh: Surely Sarah retained the ways of women in general; Rashi must clarify that this refers to menstruation.
Rashi writes: "... had ceased from her." But Rashi (to 18:8) said that she had become a Nidah that very day!
Gur Aryeh: At the time, it was an irregular occurrence; Sarah did not [yet] have "the way of women" who see at regular intervals. Also refer to 18:8:1:1*.
