Guru Nanak Dev Ji stayed at Saidpur, now Eminabad, with Bhai Lalo, a carpenter, and ate the coarse bread of his household rather than attend the feast of Malik Bhago, the local official.
Summoned to explain, the account says he took bread from each hand and squeezed them: milk came from Bhai Lalo's and blood from Malik Bhago's, because one was earned by work and the other extracted from others.
The story is the standard illustration of kirat karo, honest labour, and of the position that the source of food matters more than its quality.
It is also the reason a carpenter is one of the best known names in the tradition and the official is remembered only as the man in the story.
Gurdwara Rori Sahib and Gurdwara Chakki Sahib at Eminabad mark the visit. The Babarvani hymns describe the sack of the same town a few decades later.
Saidpur is Eminabad in Gujranwala district, and the account is set during Babur's campaign, when Guru Nanak Sahib Ji was there and recorded what he saw in the Babarvani hymns.
The story is that the food of the carpenter and the food of the rich man were squeezed, and one gave milk and the other blood. It is a parable about where what is offered came from, not about how good it was.
Bhai Lalo was a tarkhan, a carpenter, of a caste ranked below the one giving the feast. The refusal is stated in economic terms rather than ritual ones, which is the whole force of it.