The term "yichud" also refers to a ritual during an Ashkenazi Jewish wedding in which the newly married couple spends a period secluded in a room by themselves.
In earlier historical periods, as early as the talmudic era,[1] the couple would have sexual intercourse at this time, but that practice is no longer current.
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?
[6] If the husband is in town (Baaloh B'ir, or Baala Bair), or, more precisely, if it is possible that he can appear suddenly, a woman may be secluded with another man in her home.
A close, long-standing relationship (Libo Gas Boh) between the wife and another man also proscribes yichud in spite of the husband's presence in town.
The lenience caused by the man's presence in town does not, however apply to his being secluded with another woman when his wife may appear suddenly.
[6] Paradoxically, if a husband gives his wife permission to be secluded with a man, the lenience does no longer apply, since she does not fear his sudden entrance.
As a consequence of this, she can be in yichud with another man in a large city, like London or New York, where the chance that he suddenly appears is non-existent.
Rabbi Shlomo Zalman Auerbach argues that if the wife is in Ramat Gan and the husband is in Tel Aviv he is still considered to be "in town".
[8] Yichud can be circumvented by the presence of other individuals (shomrim, guards or Chaperones), who would serve to provide a check on the man's behavior.
Female relatives that permit yichud are: a man's mother; his daughter or granddaughter; his sister; his grandmother; and a woman's mother-in-law, daughter-in-law and sister-in-law.
Moses Isserles follows this view, and states that yichud with one woman and several men is prohibited only for promiscuous people.
[11] Yichud between a brother and a sister above the age of Bar and Bat Mitzvah is considered appropriate for a short term, but not when their parents are away for an extended period of time.
The Gemara explains that God was moved by the prayers of the Great Assembly to curtail the yetzer hara for incest so there is no need for a prohibition when it comes to biological parents and children.
Ovadia Yosef is essentially lenient about this issue, though he believes that it is preferable to adopt a girl so that the wife who is home most of the time can prevent yichud with the husband from occurring.
Dov Berish Weidenfeld, Yaakov Yisrael Kanievsky, Ezra Ettiah, Avrohom Yeshaya Karelitz, and Shmuel Wosner take the same position.
[7][11] According to some poskim, sleeping in the same house if other family members are present does not violate yichud laws, but should be avoided due to tzniut considerations.
[11] Others, including Moses Isserles and Joseph Soloveitchik, however, disagree about this and would not permit sleeping in the home of their future in-laws.
[5] Although mingling of men and women does not violate the prohibition of yichud, it should nonetheless be avoided, even if it is for the purpose of fulfilling a mitzvah.
[7][13] Regardless of whether yichud takes place or not, girlfriend/boyfriend relationships are forbidden, since dating, according to halacha, should not serve other purposes than finding a suitable marriage partner.
The situation may be evaded by the presence of another boy or girl aged 6–9, or, such children lacking, by giving a key to the neighbors and asking them to come in unexpectedly.
An exception is, according to Moshe Feinstein, a male patient who has been diagnosed as impotent, but in this case marit ayin calls for carefulness.
For tzniut considerations, the woman had better sit in the rear if the man is driving (or vice versa), and engaging in prolonged conversation is not advisable.
[18] On a bus, train or airplane, sitting adjacent to a member of the opposite gender is permitted, but many Orthodox Jews follow stringencies to avoid this due to the laws of negiah and tzniut.