Is biting one's nails disliked (makruh) in Islam, and what is the reason for that?

It is advisable to consult a psychiatrist if the habit of nail-biting has been present since childhood, as it may indicate psychological problems. As for its religious ruling, this habit is reprehensible and considered one of the bad habits. It can cause health problems due to dirt accumulated under the nails or damage that may be inflicted upon the nails and teeth. Therefore, a person should compel themselves to abandon it, for as the Prophet, peace and blessings be upon him, said: "Knowledge is acquired through learning, and forbearance is acquired through forbearance."