Sources from the Torah
(22) Thou shalt not lie with mankind, as with womankind; it is abomination.
Babylonian Talmud, Yevamot 76a
[Concerning] women who practice lewdness with one another . . . the action is regarded as mere obscenity.
"It is forbidden to destroy [improperly emit] seed. Therefore, a man may not practice coitus interruptus" (Maimonides, Mishneh Torah, Isuray Biah 21:18).
"[In antiquity], Jews and most other people believed that it was the man and his semen who provides the actual life, the "seed," and that the woman was merely the soil, so to speak, in which the seed grew to maturity to be born. It was considered almost like murder to allow the "seed" to be wasted through masturbation, homosexuality, or sexual intercourse without intent to procreate. It was also erroneously believed...that semen, "the precious fluid," was limited in quantity so that if it was "wasted", the energy and strength of the man would thereby be reduced" (Mary Calderone and Eric Johnson, The Family Book about Sexuality, p. 158, quoted by Rabbi Michael Gold, p. 107, retrieved from Teaching Hot Topics, p. 307).
David
(א) וַיְדַבֵּ֣ר שָׁא֗וּל אֶל־יוֹנָתָ֤ן בְּנוֹ֙ וְאֶל־כָּל־עֲבָדָ֔יו לְהָמִ֖ית אֶת־דָּוִ֑ד וִיהֽוֹנָתָן֙ בֶּן־שָׁא֔וּל חָפֵ֥ץ בְּדָוִ֖ד מְאֹֽד׃
(1) And Saul spoke to Jonathan his son, and to all his servants, that they should slay David; but Jonathan Saul’s son delighted much in David.
(1) And it came to pass, when he had made an end of speaking unto Saul, that the soul of Jonathan was knit with the soul of David, and Jonathan loved him as his own soul. (2) And Saul took him that day, and would let him go no more home to his father’s house. (3) Then Jonathan made a covenant with David, because he loved him as his own soul. (4) And Jonathan stripped himself of the robe that was upon him, and gave it to David, and his apparel, even to his sword, and to his bow, and to his girdle.
Modern Commentators
"'When you ask me to say something about being a Jewish lesbian, what can I say? You know of course that there are no Jewish lesbians because to begin with Jews are not supposed to be sexual. Especially Jewish women.' For a Jewish woman to adopt a sexual identity, and even more to adopt a lesbian identity, is to challenge the myths of the asexual Jewish woman and of an asexual Judaism." - Irena Klepfisz, "Resisting and Surviving in America", quoted in Eros and the Jews, David Biale, p. 225.
"I, for one, cannot believe that the G-d who created us all produced a certain percentage of is to have sexual drives that cannot be legally expressed under any circumstances. That is simply mind-boggling -- and, frankly, un-Jewish . . . Furthermore, it seems to me that to ask gays and lesbians to remain celibate all their lives is not halakhically required. If gays and lesbians are right in asserting that they have no choice in being homosexual . . . then they are as forced to be gay as straights are forced to be straight . . . " - Rabbi Elliot Dorff, Matters of Life and Death, p. 145.
"There are other ways . . . of contributing to the survival of the Jewish people, aside from physically begetting or bearing children: many Jewish homosexuals support worthy Jewish causes and institutions . . . some make their contributions as teachers of Judaism . . . " - Rabbi Herschel Matt, Conservative Judaism, Spring 1987.
"Homosexuality is no different from any other anti-social or anti-halakhic act, where it is legitimate to distinguish between the objective act itself, including its social and moral consequences, and the mentality and inner development of the person who perpetuates the act . . . To use halakhic terminology, the objective crime remains a ma'aseh avayrah (a forbidden act) whereas the person who transgresses is considered innocent on the grounds of ["oh-ness"] (force beyond one's control)." - Rabbi Norman Lamm, "Judaism and the Modern attitude toward Homosexuality," Encyclopedia Judaica Yearbook, 1974.
"The Jewish values and principles which I regard as eternal, transcendent and divinely ordained, do not condemn homosexuality. The Judaism I cherish and affirm teaches love of humanity, respect for the spark of divinity in every person, and the human right to live with dignity. The G-d I worship endorses loving, responsible, and committed human relationships, regardless of the sex of the persons involved." - Janet Marder, "Jewish and Gay," Keeping Posted 32, 2; November, 1986.
"Whereas justice and human dignity are cherished Jewish values, and whereas, the institutions of Reform Judaism have a long history of support for civil and equal rights for gays and lesbians, and whereas, North American organizations of the Reform Movement have passed resolutions in support of civil marriage for gays and lesbians, therefore we do hereby resolve, that the relationship of a Jewish, same-gendered couple is worthy of affirmation through appropriate Jewish ritual . . ." - Ad Hoc Committee on Human Sexuality, CCAR, 1998.
"We favor the establishment of committed and loving relationships for gay and lesbian Jews. The celebration of such a union is appropriate with blessings over wine and shehechayanu, with psalms and other readings to be developed by local authorities... Yet can these relationships be recognized under the rubric of kiddushin (Jewish marriage)? . . . We are offering two model ceremonies, one that closely follows the traditional Jewish wedding liturgy, and one that starts fresh. Each ceremony accomplishes the following tasks which we consider to be essential to any Jewish marriage ceremony: A) The couple is welcomed, and G-d's blessings are requested for their marriage. B) Traditional symbols of celebration - such as wine - and of commitment - such as rings - are used to add significance to this moment. C) A document of "covenant" committing the couple to live a life of mutual fidelity and responsibility is read and witnessed. This covenant is affirmed at the rings ceremony and constitutes the halakhic mechanism for binding the couple together as a family. D) Blessings thanking G-d for this sacred moment of loving covenant are recited, and the couple's relationship is linked to the broader narrative of the Jewish people and its redemption." - Rabbis Elliot Dorff, Daniel Nevins, and Avram Reisner, "Rituals and Documents of Marriage and Divorce for Same-Sex Couples, RA, 2012.
"To be a self-accepting gay or lesbian person, one generally must go through a certain process of negation and affirmation. In homophobic societies, one is told that how one loves is wrong. Yet, at some point, to live a full life, one must learn for oneself that these statements are wrong and that love is right. This inversion teaches, in an experiential way, the primacy of love. It forms a unique mode of moral conscience, and teaches in a distinctive way what it is to love G-d b'chol levavcha, b'chol nafshecha, uv'chol meodecha, with all your heart, body, mind, and spirit. And it engenders the queer mysticism we read in Rumi, Hafiz, and Judah HaLevy . . . " - Jay Michaelson, The Passionate Torah: Sex and Judaism, 2009, p. 218.