Sayyidah Aishah (may Allah be pleased with her) said that a woman gave her a tray full of dates as a gift. Sayyidah Aishah (may Allah be pleased with her) ate some of them, and some were left on the plate. The woman said: I adjure you by an oath to eat all of it. He (peace and blessings be upon him) said: "Fulfil her oath, for the sin is upon the one who causes the oath to be broken."
The hadith of Abu Hurayrah (may Allah be pleased with him) has in its chain someone unknown from among the shaykhs of Baqiyyah. The hadith of Aishah is better, but it is mursal.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 19892