Musnad Ahmad 1013:19

'Abd al-Samad narrated to us, saying: 'Abd al-Rahman—meaning Ibn 'Abd Allah ibn Dinar—narrated to us, Abu Hazim narrated to us, from Sahl ibn Sa'd, that it was said to him: "Did the Messenger of Allah (peace and blessings of Allah be upon him) see *al-naqi* (refined flour) with his own eyes before his death?"—meaning *al-hawwari* (white flour). He said: "The Messenger of Allah (peace and blessings of Allah be upon him) did not see *al-naqi* with his own eyes until he met Allah, the Almighty and Majestic." It was said to him: "Did you have sieves during the time of the Messenger of Allah (peace and blessings of Allah be upon him)?" He said: "We did not have sieves." It was said to him: "Then how did you prepare the barley?" He said: "We would blow upon it, and whatever would fly away from it would fly away."