Musnad Ahmad 962:10

'Abd al-Malik ibn 'Amr narrated to us, Hisham narrated to us, from Yahya ibn Abi Kathir, from Abu Salam, from Abu Umamah, who narrated to him, saying: I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: "Recite the Quran, for it will be an intercessor for its companions on the Day of Resurrection. Recite the two radiant ones: Al-Baqarah and Al-'Imran, for they will come on the Day of Resurrection as if they were two clouds, or as if they were two shades, or as if they were two flocks of birds in ranks, pleading for their people." Then he said: "Recite Al-Baqarah, for taking it is a blessing, leaving it is a regret, and the sorcerers cannot withstand it."