`Aishah (May Allah be pleased with her) said: The Prophet (PBUH) said, "None of you should say: `My soul has become evil. He should say: `My soul is in bad shape."[Al-Bukhari and Muslim].
Khabusatu and Laqisatu are synonymous but the former has appearance of greater sinfulness. Imam Al-Khattabi says that this is a guidance for speaking in a proper manner. One should always use a decent word and abstain from impolite language.