Is one who commits a sin out of ignorance of the ruling – because he did not inquire about it – sinful, or not?

A person is excused if they commit a prohibited act out of ignorance of its prohibition, based on the Almighty's saying: "And there is no blame upon you for what you have erred in, but [there is blame for] what your hearts intended." However, being excused from the sin does not mean being excused for negligence in seeking obligatory knowledge. Many jurists stipulated knowing Allah's ruling before undertaking an action. And whoever commits a sin out of ignorance, when it is something known to be an essential part of the religion, is sinful for their action and for their neglect of learning. But if it is not something essentially known, then they are not sinful for their action, but they are sinful for neglecting to learn.