Whoever leaves no heir except a slave he freed, the inheritance goes to him

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that a man died, and the Prophet (peace and blessings be upon him) said: "Look for an heir of his." But no heir was found except a freed slave (mawla) of his, so the Messenger of Allah (peace and blessings be upon him) said: "Give the inheritance to him."
This hadith is sahih (authentic) on the condition of Imam Bukhari, but the two Shaykhs (Bukhari and Muslim) did not record it. However, Hammad bin Salamah and Sufyan bin Uyaynah narrated it from Amr bin Dinar, from Awsajah the freed slave of Ibn Abbas, from Ibn Abbas.

According to the narration of Hammad bin Salamah, it is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that in the blessed time of the Messenger of Allah (peace and blessings be upon him), a man died and left no heir or close relative except the slave he had freed, so the Prophet (peace and blessings be upon him) gave the inheritance to that slave.

Awsajah (the freed slave of Ibn Abbas) narrates: I heard Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) say that in the blessed time of the Messenger of Allah (peace and blessings be upon him), a man died who left no heir or relative except the slave he had freed, so the Prophet (peace and blessings be upon him) gave his inheritance (to that slave).

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that people brought before Sayyiduna Ali (may Allah be pleased with him) the case of the child of a woman who underwent li'an. The 'asabah (relatives) of his father came demanding his inheritance, whereupon Sayyiduna Ali (may Allah be pleased with him) said: Indeed, his father had disowned him (through li'an). So he gave his inheritance to his mother, made her his 'asabah, and gave those people nothing.
This hadith has a sahih (authentic) chain of narration; although it is mawquf as a ruling of the Commander of the Faithful, it is a rare narration among his fatwas and rulings.