Hadith #349 (Sunan Ibn Majah)
Book: The Book of Purification and its Sunnah
Narrator(s): al-Fadl bin Dakayn, Abu Na'eem الفضل بن دكين أبو نعيم الملائي, Ali bin Muhammad bin Ishaq al-Tanafasi علي بن محمد بن إسحاق الطنافسي, Isa bin Yzdad عيسى بن يزداد, Muhammad bin Yahya bin Hiban محمد بن يحيى بن حبان, Waki' bin al-Jarrah وكيع بن الجراح, Zm'h bin Salah زمعة بن صالح

“The Messenger of Allah said: ‘No one of you should bathe in open land or on a roof where he is not concealed; even if he does not see anyone, he can still be seen.'”

Source: https://parallelquran.com/hadith/sunan-ibn-majah-349/