Mishnah Sotah 3:4
משנה סוטה ג׳:ד׳
Mishnah Sotah 3:4
Contains the famous teaching of Rabbi Eliezer that one who teaches his daughter Torah is as if he teaches her tiflut, a foundational source in discussions of women’s Torah study.
מִכָּאן אוֹמֵר בֶּן עַזַּאי, חַיָּב אָדָם לְלַמֵּד אֶת בִּתּוֹ תוֹרָה, שֶׁאִם תִּשְׁתֶּה, תֵּדַע שֶׁהַזְּכוּת תּוֹלָה לָהּ. רַבִּי אֱלִיעֶזֶר אוֹמֵר, כָּל הַמְלַמֵּד אֶת בִּתּוֹ תוֹרָה, כְּאִלּוּ מְלַמְּדָהּ תִּפְלוּת.
From here Ben Azzai states: A person is obligated to teach his daughter Torah, so that if she drinks and does not die immediately, she will know that some merit she has delayed punishment for her. Rabbi Eliezer says: Anyone who teaches his daughter Torah is teaching her promiscuity [tiflut].