Sahih Bukhari Volume 9, Book 93, Hadith Number 548.

Narrated By ‘Abdullah : While I was walking with Allah’s Apostle in one of the fields of Medina and he was walking leaning on a stick, he passed a group of Jews. Some of them said to the others, “Ask him (the Prophet) about the spirit.” Others said, “Do not ask him.” But they asked him and he stood leaning on the stick and I was standing behind him and I thought that he was being divinely inspired. Then he said, “They ask you concerning the spirit say: The spirit, its knowledge is with My Lord. And of knowledge you (O men!) have been given only a little.”… (17.85) On that some of the Jews said to the others, “Didn’t we tell you not to ask?”