I say, and with God's success: His leftover is pure and purifying for the event, as it removes real impurity from the garment and body, and it removes legal impurity, which is the event and ritual impurity, meaning it is permissible to perform ablution and bathing with it, unless there is impurity in his mouth. However, if his mouth becomes impure, then if he drinks water immediately, his leftover would be impure. But if he had saliva in his mouth several times and then spit it out or swallowed it before drinking, then his leftover would not be impure. There is no difference in the ruling of the leftover of a human being between the adult and the child, the Muslim and the non-Muslim, the menstruating woman and the one in a state of ritual impurity; as narrated by Aisha, may Allah be pleased with her, who said: "I used to drink while I was menstruating, then I would hand it to the Prophet (peace be upon him) and he would place his mouth on the spot in my mouth and drink," in Sahih Muslim 1: 245, Sahih Ibn Khuzaymah 1: 58, and Sahih Ibn Hibban 4: 108. See: Maraqi al-Falah, p. 29, and Allah knows best.