Is it permissible, in Islamic law, for my friend to receive a portion of the compensation amount resulting from a lawsuit filed by the owners of an Arabic song's melody against a foreign singer who stole the melody and used it in a song with vulgar lyrics, given that he assisted them in the litigation procedures?

Singing and music are forbidden (haram (definition)), for they are the gateway to immorality, corruption, and shamelessness. Their prohibition has been mentioned in the Quran and Sunnah (definition). From the Quran, Allah Almighty says: "And of the people is he who buys the amusement of speech to mislead [others] from the way of Allah." Ibn Abbas and Ibn Mas'ud interpreted "amusement of speech" as singing. From the Sunnah, there are numerous narrations prohibiting singing and musical instruments, such as the Prophet's (peace be upon him) prohibition of selling and buying female singers, and his saying: "There will be among my Ummah people who will consider unlawful sexual intercourse, silk, intoxicants, and musical instruments as lawful." Since singing and music are forbidden, contracts for the sale or rental of anything related to them are null and void, and the money earned from them is unlawful (haram) and should not be taken or enjoyed.