(a) Asma bint Abi Bakr (may Allah be pleased with her) said that the Prophet (peace and blessings be upon him) ordered this, that is, "the freeing of slaves."
The wording about freeing slaves in the narration of Hisham from his father from Aishah is gharib (unusual); the well-known version is from Hisham from Fatimah bint al-Mundhir from Asma bint Abi Bakr.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة الخسوف / 6365