What is the ruling on a student of knowledge going out to seek knowledge if his parents forbid him from doing so?

If there is a necessity for the student to remain with his parents, then their dutifulness takes precedence over seeking knowledge, especially if they are in need of him. However, if they are not in need of him and his going out to seek knowledge is better, then there is no harm upon him, while observing their right to return and convince them. If the parents' dislike for Shar'i knowledge is the reason for their refusal, then there is no obedience to them in that, and he is not required to seek their permission.