Musnad Ahmad 26:348

Uthman ibn Muhammad ibn Abi Shaybah narrated to us—Abdullah ibn Ahmad said: And I heard it myself from Uthman ibn Abi Shaybah—Abdullah ibn Idris narrated to us, from al-A’mash, from Abdullah ibn Murrah, from Masruq, from Abdullah, who said: While the Prophet, peace and blessings of Allah be upon him, was in a cultivated field, leaning upon a palm branch, a group of Jews stood up to him and asked him about the soul. He remained silent. Then he recited this verse to them: "They ask you about the soul. Say, 'The soul is of the affair of my Lord, and you have not been given of knowledge except a little.'" [Al-Isra: 85]