Though much of Jewish philosophy focuses on the values and obligations of the family unit, as well as the elements necessary for good political leadership, the sages have also had a lot to say about the role friendship plays in Judaism. In fact, friendship is considered one of the great virtues a person must acquire in order to truly understand Torah, also known as the Middot Torah. The specific Middah Torah concerning friendship is known as Dibbuk Chaverim, a Hebrew term that literally translates as "Binding of Friends", or at least binding in the sense of forming a union. Dibbuk is a binding by fusion, whereas the term Akedah is a binding by force, as with a rope, while Shasheret means binding as two links in a chain are bound (also metaphorically applied to the binding of two lives in marriage). Dibbuk Chaverim indicates a kind of equality in the union, as well as a mixing of personalities. Plainly, the Jewish concept of friendship focuses on the influence two people can have on one another.
Arguably the most important aspect of friendship in Judaism is the notable lack of obligation or contract. While all other relationships in the Jewish perspective are characterized by a series of duties clearly defined in the Torah, from parenthood to marriage to business associations, there are no such measures of propriety or legality among friends. This makes friendship both freer and more fragile than any other kind of relationship. All acts of kindness, support or justice among friends are entirely willful. This is one of the reasons why true friendship is a prized virtue in the eyes of the sages. It is goodness compelled by no other force than the desire to do good.
Friendship in Judaism also has a more practical side. In the study of Talmud, for instance, it is the tradition for people to study in pairs. This is because an individual alone has access to only his or her own insight, whereas a partnership allows students to share their ideas and point things out to one another that they would have missed had they been studying alone.
Outside of study, the sages also pointed out the value of friendship in everyday life. In the Pirkei Avot, the Talmudic collection of moral and ethical wisdom of the great commentators, it is stated, "...woe to him who is alone when he falls and there is no one to lift him." This passage recognizes that life can be difficult and that everyone has moments of personal struggle. It is then the ability of one's friends to be a system of support where all else has failed. We help our friends not because we must, but because the world is made better when we do. This is the very core of Tikkun Olam, the repair of the world.
In the the written works of the Torah, one of the strongest examples of friendship is that between David and Jonathan. Jonathan is the son of King Saul, who would eventually become David's enemy. In David's youth when he was welcome in Saul's court, he and Jonathan developed a kinship that surpassed any other relationship either of them ever experienced. Jonathan was David's truest friend, ultimately saving David's life. The Book of Samuel, in which this story can be found, is nothing if not a collection of examples of people failing in their relationships and responsibilities. Jonathan and David's friendship stands out as the one example of unfaltering goodness and it turns out to be a pivotal moment in David's journey.
So, though Judaism doesn't bind friends together by contract or by moral decree, it still recognizes that friends can have a significant impact on our lives. True, unwavering friendship is vital for the understanding of Torah because it is perhaps the greatest example of pure compassion in the human experience.