Authentic Supplication Number 041.

'Anas  said: The Prophet  was such that if he would enter the privy, he would say Bismillahi, 'allahumma 'innee 'a`outhu bika minal-khubthi wal khaba'ithi (64).

Footnotes.
(64) In the Name of Allah; my 'ilah I seek refuge in You from the male, and female devils (shayateen, which is the plural for shaytan).

Reporters.
Reported by 'Ibn 'Abi Shaybata, and Abu Dawood. Al-Albani said it was sound in Saheeh Al-Jami` As-Sagheer wa Ziyadatih and it is in his Saheeh Abu Dawood. This supplication, without the Bismillahi, was said to be sound by 'Al-`Adawee and he said that it was reported by Al-Bukhari, page 343 of volume 1 of Fath Al-Baree; Ahmed, pages 99, 101, and 383 of volume 3, and on pages 369 and 373 of volume 4 as part of the hadeeth of Zaid bin Al-Arqam; Muslim, #375 according to the print of Abu Dawood, page 15 of volume 1; Ibn Majah, #298; An-Nisa'ee, page 30 of volume 1; At-Tirmithi who said it was comely-sound, and still others.