It was narrated that Rifa'ah bin 'Arabah A-Juhani said: "The swearing of the Messenger of Allah (ﷺ) when he took an oath and I bear witness before Allah was: “By the One in Whose Hand is my soul”"
SahihSahihSahihBook 11 · Hadith 2
سنن ابن ماجه
It was narrated that Rifa'ah bin 'Arabah A-Juhani said: "The swearing of the Messenger of Allah (ﷺ) when he took an oath and I bear witness before Allah was: “By the One in Whose Hand is my soul”"