Imam al-Shafi'i (may Allah have mercy on him) said: There is disagreement concerning the female apostate. Some people's evidence is the narration of Ibn Abbas (may Allah be pleased with them both) that she is to be imprisoned and not killed. Some of those who hold this view spoke with me while a group of the scholars of hadith were present with us, so we asked them about this hadith, and I do not know of a single one of them who held back from saying: This is a mistake, and the one who narrated it is not among those whose hadith the people of hadith accept as established. Imam al-Shafi'i (may Allah have mercy on him) said: Some have narrated from Sayyiduna Abu Bakr (may Allah be pleased with him) that he killed women who had apostatised from Islam, so why was that not adopted?
Hadith Referenceالسنن الكبرى للبيهقي / كتاب المرتد / 16871