Asking for Qur'aan without Sunnah?

It is reported that ‘Imraan b. Husayn – Allaah be pleased with him – was once relating hadeeth amongst a group of people, when a man said:

Leave this and give us something from the Book of Allaah. ‘Imraan said, “You are a dunce (stupid). Do you find in the Book of Allaah details of prayer? Do you find in the Book of Allaah details of fasting!? This Qur`aan prescribes those matters, and the Sunnah explains them.”

Al-Harawee, Dham Al-Kalam article 244, et al with various wordings