Oogardanti Baani of Guru Gobind Singh, as included in the Dasam Granth, speaks of cow killing as a sin. Guru Gobind Singh has written that:
“Give me this command that I may grab Turks and destroy them. The great evil of cow-killing may I stop in this world. The throne of the Mughals may I destroy”
“Fulfil this desire of mine. May the suffering of cows stop. May the victory of the true Guru resound throughout the world.
However, it may be reasoned that the name ‘cow’ used by Guru Gobind Singh is a reference to the weak, like cows, a defenseless and peaceful beast. Whilst the regime, at the time, is referred to as the cow-killer – “gau ghaat” …
Jassa Singh Ahluwalia took up arms to kill cow butchers several times, Giani Gian Singh speaks of the actions of Jassa Singh Ahluwalia as: “Though, he was very against the killing of cows. To stop this, he attacked many times Lahore and Kasur, and slayed the cow butchers.” - Twarikh Guru Khalsa, Giani Gian Singh (1894), Pa 734
Bhai Gurdas, the scribe of Guru Granth Sahib, said “cow dung, cow's urine, and silk are considered sacred…”
In some English translations, this is translated as “According to Hindu mythology, cow dung and cow's urine are considered sacred…” Even though the original Gurmukhi wordings do not contain or mention “According to Hindu mythology” anywhere.