Musnad Ahmad 30:866

Mu'adh ibn Hisham narrated to us, my father narrated to me, from Qatadah, from al-Hasan, from Abu Rafi', from Abu Hurairah, that the Prophet of Allah, may Allah bless him and grant him peace, said: "If one of you knew that if he attended the prayer with me, he would have something greater than a fat sheep or two fat sheep, he would do so. And what he attains of reward is better."