Sahih Muslim Book 5, Hadith Number 2322.

Chapter : Exhortation to kill the Khwarij.

Abu Salama and ‘Ata’ b. Yasar came to Abu Sa’id al-Khudri and asked him about Haruriya, saying: Did you hear the Messenger of Allah (may peace be upon him) making a mention of them? He (Abu Sai’d al-Khudri) said: I don’t know who the Haruriya are, but I heard the Messenger of Allah (may peace be upon him) as saying: There would arise in this nation (and he did not say “out of them”) a people and you would hold insignificant your prayers as compared with their prayers. And they would recite the Qur’an which would not go beyond their throats and would swerve through the religion (as blank) just as a (swift) arrow passes through the prey. The archer looks at his arrow, at its iron head and glances at its end (which he held) in the tip of his fingers to see whether it had any stain of blood.