What is the ruling on a person saying about another that he is Allah's prophet on Earth, and what is the ruling on remaining silent about that, Islamically?

It is not permissible to say that someone is a prophet in our current era, for Muhammad, peace and blessings be upon him, is the Seal of the Prophets and Messengers. And whoever claims prophethood after him, or believes in it for someone else, is a disbeliever by the consensus of the Muslims, as the religious texts are consecutively transmitted regarding this, such as His (Allah's) saying: (Muhammad is not the father of [any] one of your men, but [he is] the Messenger of Allah and the Seal of the Prophets.) [Al-Ahzab:40], and his (peace and blessings be upon him) saying: "I have been favored over the prophets with six things: I have been given comprehensive words, I have been aided with awe, spoils of war have been made lawful for me, the earth has been made pure and a place of prostration for me, I have been sent to all creation, and the prophets have been sealed with me."

Whoever makes such a claim or believes it should be advised and warned of Allah's punishment. If he does not recant, then he is a disbeliever, an apostate, and should be shunned. The Companions fought those who claimed prophethood after the death of the Prophet, peace and blessings be upon him.