Sahih al-Bukhari 5410
Sahih al-Bukhari · Book 70: Food, Meals · To blow barley (to remove the husk).
Narrated Abu Hazim:
حَدَّثَنَا سَعِيدُ بْنُ أَبِي مَرْيَمَ ، حَدَّثَنَا أَبُو غَسَّانَ ، قَالَ حَدَّثَنِي أَبُو حَازِمٍ ، أَنَّهُ سَأَلَ سَهْلاً هَلْ رَأَيْتُمْ فِي زَمَانِ النَّبِيِّ صلى الله عليه وسلم النَّقِيَّ قَالَ لاَ. فَقُلْتُ فَهَلْ كُنْتُمْ تَنْخُلُونَ الشَّعِيرَ قَالَ لاَ وَلَكِنْ كُنَّا نَنْفُخُهُ.
that he asked Sahl, "Did you use white flour during the lifetime of the Prophet (ﷺ) ?" Sahl replied, "No. Hazim asked, "Did you use to sift barley flour?" He said, "No, but we used to blow off the husk (of the barley).