Sunan an-Nasa'i, Hadith 3779 ⓘ
It was narrated from Abu Musa that the Prophet said: "There is nothing on Earth that I swear an oath upon, and I see that something else is better, but I do that which is better."
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا ابْنُ أَبِي عَدِيٍّ، عَنْ سُلَيْمَانَ، عَنْ أَبِي السَّلِيلِ، عَنْ زَهْدَمٍ، عَنْ أَبِي مُوسَى، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " مَا عَلَى الأَرْضِ يَمِينٌ أَحْلِفُ عَلَيْهَا فَأَرَى غَيْرَهَا خَيْرًا مِنْهَا إِلاَّ أَتَيْتُهُ " .
also referenced under: Book 35, Hadith 19 (In-Book) & Volume 4, Book 35, Hadith 3810 (DarusSalam)