Q 2: What is the ruling on a person who changes their father's name out of ignorance for the sake of a worldly gain?

A: It is not permissible for a person to change their father's name for the sake of a worldly gain. This is because such gain is one of two things. First: Notability on the ground of associating themselves with a different person and disdaining being related to their father which is a major sin as it entails lying, falseness, and degrading the father. Second: Earning money via inheritance, judged compensation, etc. This is also a major sin as it comprises lying, deception, and devouring people's money unjustly. This also changes lineages and leads to the alteration of descents and consequently creates ambiguity. Changing a person's father's name is a means to considering Haram (prohibited) things relating to marriage, properties, etc., that Allah (Exalted be He) declares Halal (lawful) and vice versa. Of course, this involves major corruption. It is worth mentioning that it is authentically reported on the authority of Abu Dhar (may Allah be pleased with him) that the Prophet (peace be upon him) said: (Part No. 20; Page No. 373)  Whoever attributes themselves to other than their own father, while knowing him, commits an act of Kufr (disbelief). Besides, it is authentically reported on the authority of Sa`d ibn Abu Waqqas (may Allah be pleased with him) that the Prophet (peace be upon him) said: Whoever claims to be the son (or daughter) of a person other than their father while they know that such person is not their father, then Jannah (Paradise) will be forbidden to them. It is reported on the authority of Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace be upon him) said: Do not detest your fathers for whoever does so commits an act of Kufr. (Related by Al-Bukhari and Muslim) The Prophet (peace be upon him) thus threatened strictly the person who claims to be the son (or daughter) of a person other than their father. He (peace be upon him) regarded such an act as being a sort of Kufr and declared Jannah forbidden to whoever indulges in the concerned sin. Accordingly, whoever claims to be the son of a person other than their father has to give up that and make Tawbah (repentance to Allah) and Istighfar (seeking forgiveness from Allah). May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.