What is the ruling on linking a medical examination to a person who is medically fit without actually examining him, and is the money earned from that permissible or forbidden, and how can one dispose of it if it is mixed with permissible money?

It is not permissible to obtain a medical certificate without an examination, because that is considered prohibited deception and lying. The Prophet, peace and blessings be upon him, said: "Whoever deceives is not of me."

Whoever does this must repent to Allah Almighty. The money earned from this action is not lawful, because it is wages for a prohibited deception, and one must spend it on charitable and good causes to rid oneself of it.