It is narrated from Hazrat Uqbah bin Aamir (may Allah be pleased with him) that I heard the Messenger of Allah (peace and blessings be upon him) say: The expiation for a vow is the same as the expiation for an oath.
Hadith Referenceمسند احمد / مسند الشاميين / 17325
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد حسن