What is the meaning of the saying, "I bear witness that Muhammad is not of humankind, and whoever says [he is] Ali ibn Talib has disbelieved," which was said to be found in the rules of the Arabic language?

This riddle is circulated among people and has no relation to the rules of the Arabic language. Their phrase "ليس بخالق" (laysa bikhaaliq) means "not caring" or "not minding." The "royal messenger" refers to Jibril (Gabriel), peace be upon him, and he does not have a cousin.