Musnad Ahmad 258:12

Al-Walid ibn Muslim narrated to us, he said: Al-Walid ibn Sulayman—meaning Ibn Abi al-Sa’ib—narrated to me, he said: Hayyan Abu al-Nadr narrated to me, he said: I entered with Wathilah ibn al-Asqa’ upon Abu al-Aswad al-Jurashi during his illness in which he died. He greeted him and sat down. He said: Abu al-Aswad took Wathilah’s right hand and wiped it over his eyes and his face because he had pledged allegiance to the Messenger of Allah (peace and blessings of Allah be upon him) with it. Wathilah said to him: "One thing, I ask you about it?" He said: "And what is it?" He said: "How is your opinion of your Lord?" He said: Abu al-Aswad said—and he gestured with his head, meaning: "Good." Wathilah said: "Rejoice, for I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: 'Allah the Almighty and Majestic says: I am as My servant thinks of Me, so let him think of Me as he wills.'"