One God is the only treasure of peace; I have heard that He is eternal and imperishable. He is entirely pervading water, land and sky; He is composed in each and every heart. He looks alike upon the high and the low, the ant and the elephant. Friends, companions, children and relatives are all created by Him. O Nanak, one who is blessed with the Naam, enjoys Lord's love and affection (Guru Granth Sahib Ji, 319).
Recognize the Lord's Light (Spirit) within all, and do not consider social class or status; there are no classes or castes in the world hereafter (Guru Granth Sahib Ji, 349).
The special feature of the Sikh of the Guru is that he goes beyond the framework of caste-classification and moves in humility. Then his labor becomes acceptable at the door of God (The Vaars of Bhai Gurdas Ji, 1).