You are children of the Lord, your God. You shall neither cut yourselves (lo titgodedu) nor make any baldness between your eyes for the dead. (Deuteronomy 14:1)
God commands the Jewish people that it is forbidden to practise self mutilation over the loss of a loved one. While someone may be wracked with grief, harming one’s body is not an appropriate expression of that grief and according to Rashi (d. 1105) was practiced by heathen sects such as the Amorites.
The Gemara (Yevamos 13b) derives another law from the phrase lo titgodedu which is not make ‘agudot agudot’ – different religious factions. At first glance, this implies a law against halachic diversity. Apart from being impractical, it would seemingly violate other principles, such as eilu v’eilu divrei Elokim chaim (these and those are the words of the living God), which indicates that multiple opinions within halachic boundaries are not only authentic, but equally valid expressions of Torah and Jewish law.
The Amoraic sages Rava and Abaye (5th Century CE) both limit the scope of this prohibition to refer to disparities in local Batei Din (Jewish courts, plural of Beth Din). The essence of each view is to prevent communities from becoming fractured.
Nowadays it is normal for a city to have a number of diverse communities and on occasion different Batei Din. Rabbi Yosef Caro (d. 1575) wrote in his responsa that since each community follows its original custom, each community is considered like a city of its own (Avkat Rachel 32).
Consequently, practical examples of Lo titgodedu apply withinone synagogue. For example, the nusach (text) of the prayer services differs between Ashkenazi and Sephardi communities. If a Sephardi Jew is asked to lead the service in an Ashkenazi Shul, he must forgo his personal custom and lead with the Ashkenazi nusach. When praying privately however, it would be acceptable to pray according to one’s own traditions.
Factionalism cannot be prevented by one monotonic set of laws and customs. On the contrary, pluralism within the boundaries of halacha makes orthodoxy rich and diverse. Yet at the same time, communal customs and practices must be safeguarded to protect their history and integrity of their heritage.