What is the ruling on "O my master, O Messenger of Allah, behold, I come to you seeking intercession through your descendants, hoping that through you I may draw near," and is it polytheism that expels one from the faith?

The statement made by someone, "Indeed, I intercede with you through children who are attributed to you, hoping to draw near to you," when addressing the Prophet, peace and blessings be upon him, is a supplication to other than Allah Almighty. This is considered polytheism (shirk) in both divinity (uluhiyyah) and servitude ('ubudiyyah), because supplication (du'a) is an act of worship, and directing it to other than Allah is polytheism. Even if it were directed to Allah, it would be an innovation (bid'ah) because it involves seeking intercession through individuals (al-dhawat). Quranic verses and Prophetic hadiths have been revealed prohibiting supplication to other than Allah, and scholars have unanimously agreed on the disbelief (kufr) of anyone who supplicates to intermediaries between himself and Allah, such as angels and prophets, and asks them to bring benefits or repel harms.