Mansur bin Abd al-Rahman, a man of Banu Abd al-Dar, narrates from his mother Safiyyah (may Allah be pleased with her) that she heard Sayyidah Aishah (may Allah be pleased with her) when she was asked about a person who says: "My wealth is in the way of Allah," or "All my wealth is for the Ka'bah": what is its expiation? Sayyidah Aishah (may Allah be pleased with her) said: "Its expiation is the same as that of an oath."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 20036