Musannaf Ibn Abi Shayba 1:6

Waki’ narrated to us, from Isra’il, from al-Zibriqan al-‘Abdi, from al-Dahhak ibn Muzahim, who said: When you enter the privy, say: "O Allah, I seek refuge in You from the filth, the impure, the wicked, the corrupting, the accursed Satan."