Is it a condition for a woman's mahram (a relative one may not marry) to be an adult?

Question : He asks: Is a boy who has not reached puberty a mahram for travel? And when must women veil themselves from him?

Answer : Yes, a young boy is not a mahram. The mahram must be an adult of sound mind, because the young boy himself needs a guardian to care for him. The purpose of the mahram is to protect the woman and safeguard her from roaming about alone or being targeted by the wicked and the sinners. The benefit of the mahram is great: it is the defense, protection, and safeguarding of the woman. It is not as the common people think. The common people give a strange explanation, saying that the purpose of the mahram is that if she dies, he will descend into her grave and untie the knots of her shroud. I have seen this defective explanation; in fact, it is a dead explanation. Descending into the grave is not exclusive to the mahram. Anyone can descend into the grave and place the woman in it. Even the Prophet (peace and blessings be upon him) was present at the burial of one of his daughters, and her husband was present. He was her father. The Prophet (peace and blessings be upon him) said: "Which of you did not have intercourse with his wife last night?" He was not her mahram, yet he descended into her grave and placed her in it. As for the talk of the common people, it has no basis. The conclusion is that it is obligatory for the mahram to be, what? An adult of sound mind. As for when women must veil themselves from him, Allah the Exalted clarified that in the Noble Qur'an, and there is no clarification like the clarification of Allah. What did He say? He said: "Or children who have not yet reached the age of knowing what concerns women."
Children are of two types: children who know what concerns women. You may find a boy looking at a woman, and if she is beautiful, he may follow her with his gaze without realizing it, but he sees with his own eyes. So it is obligatory to veil from him. The other type does not know about these matters, and his heart is not attached to women, so it is not obligatory to veil from him. For this reason, we may say that a boy who is nine years old must be veiled from, while a boy who is ten years old does not require veiling. Based on what? Based on the fact that Allah did not tie the ruling to specific ages.
Rather, He tied it to a description, which is: . Children differ; perhaps a boy sits with his father and his father's companions, and their talk is always about women. In that case, he has knowledge and desire. He may sit with others whose only concern is buying and selling or farming and the like. You find the boy interested in buying and selling and farming. Therefore, Allah the Mighty and Majestic set the limit for the matter by a description, which is: . Yes. May Allah reward you. Yes, but the general rule is that a boy who has reached ten years of age will come to know the 'awrah (the part of the body that must be covered) of women, and thus...