Supplication b4 entering the toilet
"In the name of Allah. O Allah, I take refuge with you from all evil and evil doers"
Supplication after leaving the toilet
"I ask You(Allah) for forgiveness"
tracted from the book: Fortification of the Muslim thru remembrance and supplication from the Qur'an and the sunnah by Sa'eed ben Ali wahf Al Qahtaani, translated by ismael ibraheem.