Narrated 'Uqba bin 'Aamir (RA):
Allah's Mssenger (ﷺ) said: "The atonement for a vow (Nadhr) is (the same as) the atonement an oath (Yamin)." [Reported by Muslim]. at-Tirmidhi added, "If he did not specify it." [And he graded it Sahih (authentic)]. (IT)
Reference (IT): Bulugh al-Maram 1385 (IT)
In-book reference (IT): Book 13, Hadith 12 (IT)
English translation (IT): Book 13, Hadith 1385 (IT)