Is it true what is said that Satan mocks a person who undresses and does not recite the supplication: "In the name of Allah, Most Gracious, Most Merciful, there is no god but Allah, He has no partner, there is no god but Him"?

The correct statement when undressing is "Bismillah" (In the name of Allah) only, based on the Prophet's (peace be upon him) hadith: "The screen between the private parts of the children of Adam and the jinn, when one of you removes his garment, is to say: Bismillah." Anything beyond that, such as "Ar-Rahman Ar-Rahim" (The Most Gracious, the Most Merciful) or "Alladhi la ilaha illa Hu" (He besides whom there is no god), has not been established. It is recommended to say "Bismillah" when putting on clothes in general, not just when entering the restroom. As for the devil laughing at those who do not say it, there is no evidence for that.