The Messenger of Allah ﷺ as saying: The atonement for a vow is the same as for an oath. Abu Dawud said: This tradition has also been transmitted by 'Amr b. al-Harith from Ka'b b. 'Alqamah, from Ibn Shamasah on the authority of 'Uqbah.  

قَالَ رَسُولُ اللَّهِ ﷺ كَفَّارَةُ النَّذْرِ كَفَّارَةُ الْيَمِينِ  

A similar tradition has also been transmitted by 'Uqbah b. 'Amir from the Prophet ﷺ through a different chain of narrators.  

عَنِ النَّبِيِّ ﷺ مِثْلَهُ