مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 3416
Oaths and Vows
Section 1
وَعَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «الْيَمِينُ عَلَى نِيَّةِ الْمُسْتَحْلِفِ» . رَوَاهُ مُسلم
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.
Mishkat al-Masabih, 3416صَحِيحٌ (الألباني)