Musnad Ahmad 799:41

Abdullah said: "I found in my father's book in his own handwriting, and it is my strongest belief that I heard it from him, he said: Ali ibn Abdullah narrated to us, Mu'adh narrated to us, he said: I found in my father's book in his own handwriting, and I did not hear it from him, Qatadah narrated to us, from Yahya ibn Malik, from Samurah ibn Jundub, that the Prophet, peace and blessings of Allah be upon him, said: 'Attend the Dhikr (sermon/remembrance), and draw near to the Imam, for a man continues to distance himself until he is delayed in Paradise, even if he enters it.'"