The heirs of the child of a woman who underwent lian are her relatives

It is narrated from Sayyiduna Wathilah bin al-Asqa' (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "A woman acquires three kinds of inheritance: that of the slave she freed, that of the abandoned foundling (laqit) she found, and that of the son concerning whom li'an (separation after an accusation of adultery) took place."
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) concerning the inheritance of the son of a woman who underwent li'an that he said: "All of his inheritance is for his mother."
All the narrators of this hadith are reliable (thiqah), and it is mursal; however, it has a supporting narration (shahid).

It is narrated from a man of the people of Syria that the Messenger of Allah (peace and blessings be upon him) said concerning the child of a woman who underwent li'an: "His mother is his 'asabah (heir)."

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that a case was brought to Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) concerning the child of a woman with whom li'an had taken place. He (may Allah be pleased with him) gave his inheritance to his mother and made her his 'asabah.
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it; and Muhammad bin Ishaq in this chain is, without any doubt, "al-Saghani".