As for the third view, it is in this narration: Uthman bin Abi Hadir (may Allah have mercy on him) said: A woman from the family of Dhu Asbah swore, saying: "Her wealth is in the way of Allah and her slave girl is free if he does not do such and such" — something her husband disliked — and her husband swore that he would not do it. Sayyiduna Ibn Abbas and Sayyiduna Ibn Umar (may Allah be pleased with them) were asked about this, and they said: "The slave girl is free, but the zakah of her wealth is to be paid."
Thus it is in this narration; and we have narrated from Sayyiduna Ibn Abbas and Sayyiduna Ibn Umar (may Allah be pleased with them) what indicates that expiation is permissible, and Allah knows best. Another view on this has also been narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 20054