Hadith 1739
'Aishah (May Allah be pleased with her) said:
عن عائشة رضي الله عنها عن النبي صلى الله عليه وسلم قال: "لا يقولن أحدكم خبثت نفسي، ولكن ليقل: لقست نفسي" ((متفق عليه)). قال العلماء معنى خبثت أي غثيت وهو معنى لقست ولكن كره لفظ الخبث
The Prophet (ﷺ) said, "None of you should say: 'My soul has become evil.' He should say: 'My soul is in bad shape."' [Al-Bukhari and Muslim].
In plain words
One should not say 'my soul has become evil,' but rather 'my soul is in bad shape.' Admitting a low mood is fine; branding the soul with the language of evil is not.
Reference : Riyad as-Salihin 1739 In-book reference : Book 17, Hadith 229