Abu Uthman narrates from Sayyiduna Sa'd (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever claims someone other than his father, knowing that he is not his father, Paradise is forbidden to him." The narrator says: I mentioned this to Sayyiduna Abu Bakrah (may Allah be pleased with him), and he said: My ears heard it and my heart retained it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللعان / 15336