Musnad Abu Ya'la al-Mawsili 242:3

Ishaq ibn Abi Isra'il narrated to us, Muhammad ibn Bakr al-Barsani narrated to us, Sa'id informed us, from Qatadah, from al-Qasim al-Shaybani, from Zayd ibn Arqam, that the Messenger of Allah (may Allah bless him and grant him peace) said: "Indeed, these privies are frequented (by devils). So if one of you wishes to enter the toilet, let him say: 'I seek refuge in Allah from the male and female devils (al-khubuth wa al-khaba'ith).'"