Langar is the free kitchen attached to every gurdwara, where anyone of any background eats the same food sitting in a line on the floor. It was instituted by Guru Nanak Dev Ji at Kartarpur and made compulsory by Guru Amar Das Ji, who would not give audience to anyone who had not eaten in it first.
In a society organised around who may eat with whom, requiring an emperor and a labourer to sit in the same row and eat the same dal is not hospitality. It is an argument.
The kitchen at the Golden Temple serves in the region of fifty thousand to a hundred thousand meals a day, more on gurpurabs, and it runs on donated grain and volunteer labour continuously.
The institution has been mobilised repeatedly for disaster relief, at earthquakes, floods and during the pandemic, and it fed the farmers' protest camps at the Delhi borders for over a year.
It is the single most widely admired Sikh institution in the world and it is five hundred years old and it has never charged anybody anything.
The rule is that everybody sits in the same line on the floor and eats the same food, and the rule is the institution. The food is incidental to what it is for.
It was established by Guru Nanak Sahib Ji at Kartarpur and made permanent by Guru Angad Dev Ji and Mata Khivi Ji at Khadur, and Guru Amar Das Ji required visitors to eat before being received.
That last requirement was aimed at Akbar as much as at anybody else. The point of it was that no exception would be made for rank, and the account of the emperor sitting to eat is the proof the tradition keeps.