It was narrated that Ibn 'Abbas said:
"The Messenger of Allah used to pray in the night (Qiyamul-Lail) two Rak'ah by two, then when he finished he would use the tooth stick." (IT)
English reference (IT): Vol. 1, Book 1, Hadith 288 (IT)
Arabic reference (IT): Book 1, Hadith 303 (IT)