ENOfficial
He reported God's Messenger as saying, "An oath is to be interpreted according to the intention of the one who takes it.” Muslim transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «الْيَمِينُ عَلَى نِيَّةِ الْمُسْتَحْلِفِ» . رَوَاهُ مُسلم
sunnah.com