Final answer:
To attend the discourse of Guru Amardas Ji, one had to partake in Guru-ka-langar, reflecting the principles of equality and community in Sikhism.
Step-by-step explanation:
Before one was allowed to attend the discourse of Guru Amardas Ji, the third Sikh Guru, it was mandatory to partake in Guru-ka-langar. Guru-ka-langar is a communal kitchen where meals are served to all visitors, without distinction of religion, caste, gender, economic status, or ethnicity.
The practice of eating together in this community kitchen was revolutionary as it upheld the principles of equality and oneness among all people, fostering a sense of community and breaking down societal barriers.