It was narrated that Abu "Uthman an-Nahdi said: I heard Sa"d say: My ears heard and my heart understood from Muhammad (ﷺ) that:

“Whoever claims to belong to someone who is not his father, knowing that he is not his father, Paradise will be forbidden to him." I met Abu Bakrah and told it to him, and he said: my ears also heard and my heart understood from Muhammad (ﷺ).