What is the ruling on attending Friday prayer in a mosque where the preacher says, "Our support is Muhammad, peace be upon him?"

What the preacher says about the Prophet Muhammad, peace and blessings be upon him, being a "support" (sanad) does not prevent attending the sermon and following him, because the word "support" carries a correct meaning, which is "one's reliance." The Prophet, peace and blessings be upon him, is indeed the reliance of people in knowing and practicing the religion, and he is the one who conveys from Allah Almighty. He is also their reliance on the Day of Judgment for intercession with the Lord of the Worlds, and his intercession will be with Allah's permission. There is no need to interpret his statement in a corrupt sense, such as seeking aid from him, for the default for a Muslim is soundness and good presumption.