Deuteronomy 13:7 says: If your very own brother, or your son or daughter, or the wife you love, or your closest friend secretly entices you, saying, 'Let us go and worship other gods, gods that neither you nor your ancestors have known...' The Talmud gives an explanation to the passage, which is supposed to be a hint of
yichud: Said Rabbi Johanan on the authority of Rabbi Ishmael, Where do we find an allusion to
yihud in the Torah? - For it is written: If thy brother, the son of thy mother, entices thee [etc.]: does then only a mother's son entice, and not a father's son? But it is to tell you: a son may be alone with his mother, but not with any other woman interdicted in the Torah. The Talmud also claims that after the rape of
Tamar, daughter of
David, when she was left alone with her half-brother Amnon, David and his high court extended this prohibition to unmarried girls as well. Later, in the times of
Shammai and
Hillel the Elder, the prohibition was extended to include a non-Jewish woman. These rules are discussed in the
Talmud. Most
rishonim define the prohibition of
yichud as a
Torah law. Although
Maimonides writes that the prohibition of
yichud is derived from
divrei kabbalah (Bible texts later than the
Pentateuch), many interpret his words as meaning that it is a Torah law, though some regard it as a rabbinic prohibition.
Rashi maintained that insofar as the prohibition of
yichud is mandated by the Torah, it is an essential prohibition, whereas rabbinical extensions of the prohibition are enacted as a fence meant to distance a person from forbidden relationships. Hence, leniencies would apply only to the rabbinic additions to the laws of
yichud.
Halachic consensus, following Maimonides, is, though, that leniencies apply even to Torah-mandated
yichud laws. == Laws ==