Post: The second pasuk in Chayei Sara reads:
|ב וַתָּמָת שָׂרָה, בְּקִרְיַת אַרְבַּע הִוא חֶבְרוֹן--בְּאֶרֶץ כְּנָעַן; וַיָּבֹא, אַבְרָהָם, לִסְפֹּד לְשָׂרָה, וְלִבְכֹּתָהּ.||2 And Sarah died in Kiriatharba--the same is Hebron--in the land of Canaan; and Abraham came to mourn for Sarah, and to weep for her.|
and Rabbenu Ephraim discusses the small kaf in the word וְלִבְכֹּתָהּ. He writes:
|א וְאַבְרָהָם זָקֵן, בָּא בַּיָּמִים; וַיהוָה בֵּרַךְ אֶת-אַבְרָהָם, בַּכֹּל.||1 And Abraham was old, well stricken in age; and the LORD had blessed Abraham in all things.|
And our Sages za'l said (Bava Batra, 16b;141a; Bereishit Rabba 59:7; Tosefta Kiddushim end of perek 5): Avraham had a daughter and בַּכֹּל was her name."
Actually, there is an amusing dispute in the Tosefta at the end of Kiddushin:
וכן אתה מוצא באברהם אבינו שברכו המקום בזקנותו יתר מנערותו שנא' (בראשית כד) ואברהם זקן בא בימים (בראשית כד) וה' ברך את אברהם בכל רמ"א שלא היתה לו בת [ר' אומר משם] ר' יהודה שהיתה לו בתRabbi Yehuda felt that the full blessing was that Avraham had a daughter, while Rabbi Meir held that the full blessing was that he did not have a daughter.
I made a similar derasha about the small kuf myself, that it referred to a daughter. Check it out to see how this all fits in.
The Rosh puts forth one of the aforementioned explanations, that according to the peshat, this is because she was old, and so he did not weep for her so much:
I don't know that I would label any explanation of the small kaf as peshat, rather than derash. I know that at specific times, people changed some letters in their sefer Torah to be larger, to spell out meaningful messages. (IIRC, I think one such Torah exists in the YU library.) I don't know that every small and large letter is a tradition to Moshe from Sinai. If so, it might be a later innovation specifically to communicate some derasha, rather than being a peshat message. There are some explanations of small letters I find to be peshat oriented. For instance, the small aleph in Vayikra might be because the vowel letter aleph at the end was not strictly necessary; or because it is immediately followed by another aleph, and as Shadal points out, in many instances of such duplicated letters at word boundaries, a letter is written small, perhaps because it was not originally written at all. Whether or not such an explanation is true, this is the sort of explanation which sits in the plane of peshat.