Hayyan Abu al-Nadr narrates that he heard Sayyiduna Wathilah (may Allah be pleased with him) say: the Messenger of Allah (peace and blessings be upon him) said: Allah, the Mighty and Majestic, says: "I am as My servant thinks of Me, so let him think of Me as he wishes."
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18430