The ruling on a student bowing to his shaykh, a son to his father, and a woman to her husband

Question:
He says: Honorable Shaykh, may Allah grant you success. There is a custom in some countries when people meet, which is for a person to bow to another person during the greeting, such as a student to his shaykh, or a son to his father, or a woman to her husband, out of respect. Is that permissible?

Answer:
This is forbidden. This is worship. This is bowing (ruku'), so this is bowing to a person. Therefore, bowing is not permissible except to Allah through bowing in prayer. As for bowing to a creation, this is bowing and worship to a creation, so this is not permissible.