Sahih Muslim Book 27, Hadith Number 5595.
Chapter : Disapproval of using the phrase: “My soul has become evil”.
‘Aisha reported Allah’s Messenger (may peace be upon him) having said: None of you should say: “My soul has become evil,” but he should say: “My soul has become remorseless.” This hadith has been transmitted on the authority of Abu Bakr with a slight variation of wording.