It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "When Allah created the intellect, He said to it: Come forward, and it came forward. Then He said to it: Go back, and it went back. He said: By My Might, I have not created anything more wondrous to Me than you. Because of you I give, because of you is the reward, and upon you rests the punishment."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 8055