Sunan Abi Dawud
Hadith #4622
Hammad said:I heard Ayyub say: Two kinds of people have lied to al-Hasan: people who believed in free will and they intended that they publicise their belief by it; and people who had enmity with and hostility (for al-Hasan), saying: Did he not say so and so? Did he not say so and so?