The oath the Prophet ﷺ used to swear by was, "No, by the One who turns the hearts."
حدثنا وكيع حدثنا سفيان عن موسى قال وكيع نرى أنه ابن عقبة عن سالم
كان يمين النبي ﷺ التي يحلف عليها لا ومقلب القلوب
Its isnad is sahih. Waki thought that Thawri's teacher was Musa bin Uqba, and that is correct, for the hadith will come at 5347 through the route of Abdullah bin Mubarak, and at 5368 and 6109 through the route of Wahib, both of them from Musa bin Uqba. Tirmidhi likewise narrated it, 2:373, through the route of Abdullah bin Mubarak and Abdullah bin Jafar, both of them also from Musa bin Uqba. Tirmidhi said, this is a hasan sahih hadith. His commentator said, it was reported by the group except Muslim. It is likewise found in al-Muntaqa, 4857.