What is meant by the Hadith: "You are the son of your father and mother if your mother spoke truthfully"? And is it permissible for a son to ask his mother this question without sin?

We do not know that this statement is a hadith elevated to the Prophet, peace and blessings be upon him, even if its meaning is correct. Ibn Hudhafah asked the Prophet, peace and blessings be upon him, "Who is my father?" He replied, "Your father is Hudhafah." The verse "O you who have believed, do not ask about things which, if they are shown to you, will distress you" was revealed to prohibit such questions that might harm the mother.