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)]. (ES)
Reference (ES): Bulugh al-Maram 1385 (ES)
In-book reference (ES): Book 13, Hadith 12 (ES)
English translation (ES): Book 13, Hadith 1385 (ES)