Upon what are the rights of Allah and the rights of His servants built, and what is the fundamental principle regarding acts of worship and worldly dealings?

The rights of Allah are based on leniency and forgiveness, whereas the rights of people are based on strictness and exactitude. The fundamental principle regarding acts of worship is tawqif (divine restriction), meaning only that which Allah has legislated is permissible, based on His saying: "Or have they partners who legislated for them of religion that which Allah has not authorized?" (Quran 42:21). As for customs, the fundamental principle concerning them is permissibility and leniency, meaning nothing is forbidden unless Allah has forbidden it, based on His saying: "Say, 'Have you considered what Allah has sent down to you of provision of which you have made [some] lawful and [some] unlawful?' Say, 'Has Allah permitted you, or do you invent about Allah?'" (Quran 10:59). Excluded from general permissibility are wealth and sexual relations, for which the fundamental principle is prohibition, and they are not permissible except with a legal proof.