Musnad Ahmad 30:857

Muhammad—meaning Ibn Ja'far—narrated to us, Shu'bah narrated to us, from Qatadah, from 'Abbas al-Jushami, from Abu Hurayrah, from the Prophet, may Allah bless him and grant him peace, that he said: "Indeed, a surah from the Qur'an, thirty verses, interceded for a man until he was forgiven, and it is: {Blessed is He in whose hand is the dominion} [Al-Mulk: 1]."