Musnad Abu Ya'la al-Mawsili 242:4

Ishaq narrated to us, al-Nadr ibn Shumayl narrated to us, Shu'bah narrated to us, from Qatadah, who said: I heard al-Nadr ibn Anas, from Zayd ibn Arqam, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, these privies are frequented (by devils), so when one of you enters them, let him say: 'I seek refuge in Allah from the male and female devils.'"