qazi noor Mohammad says Sikhs are pig eaters.

[shastarSingh]

qazi noor Mohammad came with Ahmad Shah Abdali in 1764. He wrote a granth called 'jangnama'. He says that Sikhs are dogs but do not call Sikhs dogs because they are lions of battlefield.

Interestingly, he refers to sikh kaum as 

'khuk khaaru paleed' which translates as impure soor(pig) eating kaum.

[Jonny101]

I have heard that during those times the Mughals and Afghans would try to infiltrate their spies into Sikh ranks. The Singhs were aware of this. So when a Muslim expressed his desire to join the Sikhs by becoming a Sikh, the Singhs would first test him by making him eat some pork to see if he is really serious about leaving Islam. So maybe Qazi noor Muhammad thought all Sikhs are pork eaters.

Another way of looking at this is pig eater is also used as a term of insult among Muslims. Qazi Noor Muhammad also called Sikhs black faced which should be seen as a term of insult rather than literally being black faced.  In South Asia when someone did something shamefully wrong their faces were blackened and paraded on a donkey.