Musnad Ahmad 8:114

Isma'il narrated to us, 'Asim al-Ahwal narrated to us, from Abu 'Uthman al-Nahdi, who said: I heard Sa'd saying: My ears heard and my heart retained from Muhammad, may Allah bless him and grant him peace: "Whoever claims [to be the son of] someone other than his father, while he knows that he is not his father, then Paradise is forbidden to him." He said: So I met Abu Bakrah and told him [about it], and he said: My ears also heard and my heart retained from Muhammad, may Allah bless him and grant him peace.