What is the ruling on adopting a foundling and attributing him to the adopter, and on the adopter's wife suckling him?

It is forbidden for a person to attribute a child who is not his own to himself, based on the Prophet's (peace be upon him) saying: "Indeed, among the greatest falsehoods is for a man to claim a lineage other than his father's," and "Whoever claims a lineage other than his father's, while knowing, Paradise is forbidden for him," and "Whoever claims a lineage other than his father's, or affiliates himself with other than his masters, upon him is the curse of Allah, the angels, and all mankind. Allah will not accept from him on the Day of Resurrection any optional or obligatory deed." As for sponsoring and caring for a child without adopting him, it is among the best acts of worship. The wife can breastfeed him while he is an infant, and if she breastfeeds him five full breastfeeds, she becomes his foster mother.