Here Jagraj Singh explains why rehet is so important in the eyes of our Guru. Taken from the the talk on the Matrix Analogy.
Sikh rehat Maryada is a code of conduct for Sikhism. This document was preceded by the Gurdwaras Act of 1925, which laid down the definition of a Sikh. In 1915 and later in 1931, attempts were made to create a modern standard rehat (“code”).
In 1950 the current Sikh Rehat Maryada was produced based upon the work of Sikh scholars, seeking to better standardise Sikh practices throughout the international community. The Damdami Taksal have their own version of the Sikh Code of Conduct, the Gurmat Rehat Maryada.
Sikh Rehat Maryada is based on earlier codes (Rehat nama), to include:
Tanakhah-nama (Nasîhatnâme) Samvat 1776 (1718-19 CE), ten years after Guru Gobind Singh gave up his mortal body.
The Prahilad Rai Rehat-namab
Sakhi Rehat ki: About 1735 CE
Chaupa Singh Rehat-nama: 1740-1765 CE (1700 CE according to Piara Singh Padam). Chaupa Singh was a member of the Guru’s retinue. He was entrusted with the care of infant Gobind Das by Guru Tegh Bahadur. Some members of Chaupa Singh’s family became martyrs with Guru Tegh Bahadur in Delhi and others served under the 10th Guru.
Desa Singh Rehat-nama: late 18th century