What the song did thay sing after making a আগুন

The answer is Kumbaya

Kumbaya অথবা Kumbayah, on Gullah it means Come দ্বারা Here. It is an African-American spiritual song from the 1930s. It enjoyed newfound popularity during the folk revival of the 1960s and became a standard campfire song in Scouting and nature-oriented organizations.
The song was originally associated with human and spiritual unity, closeness and compassion, and it still is, but আরো recently it is also cited অথবা alluded to in satirical অথবা cynical ways which suggest false moralizing, hypocrisy, অথবা naively optimistic মতামত of the world and human nature.

Here are the lyrics they sang in the movie:

Kumbaya my Lord, Kumbaya
Kumbaya my Lord, Kumbaya
Kumbaya my Lord, Kumbaya
O Lord Kumbaya

kumbiya (spelled that wrong)