Musnad Ahmad 1302:30

'Abd al-Samad and 'Affan narrated to us, they said: Hammam narrated to us. 'Affan said in his narration: Hammam narrated to us, he said: Qatadah used to narrate it to us, he said: Salim ibn Abi al-Ja'd al-Ghatafani narrated to us, from the narration of Ma'dan ibn Abi Talhah al-Ya'mari, from the narration of Abu al-Darda', narrating it from the Prophet of Allah, may Allah bless him and grant him peace, and he mentioned the like of it. Then he returned to the narration of 'Abd al-Samad, he said: Hammam narrated to us, Qatadah narrated to us, from Salim, from the narration of Ma'dan, from Abu al-Darda', narrating it from the Prophet of Allah, may Allah bless him and grant him peace, that he said: "Whoever memorizes ten verses from Surat al-Kahf..."