What is the ruling on affiliation with a tribe in official documents (such as a passport) that differs from one's original tribe, while disclosing the original tribe when asked, knowing that there is kinship, friendship, and alliance between the two tribes, and that this affiliation dates back to an ancient historical designation?

A Muslim is not permitted to ascribe himself to a tribe other than his own, according to the Prophet, peace and blessings be upon him: "No man who knowingly claims to be the son of someone other than his father but disbelieves, and whoever claims a people to whom he has no lineage, let him take his place in Hellfire." The disbelief here is minor disbelief, but it indicates the prohibition of the act and that it is one of the major sins.

However, if a person joins another tribe through alliance or clientship, he is permitted to ascribe himself to it, and he is also permitted to ascribe himself to his original tribe, and to combine the two lineages; because the ally of a people is considered one of them, and the client of a people is considered one of them, and the nephew (son of a sister) of a people is considered one of them.