They were with the Prophet ﷺ at as-Sahba, which is a stage's journey from Khaybar, when the time for prayer arrived. He called for food, but nothing was found except parched barley meal. He chewed some of it and we chewed along with him. Then he called for water, rinsed his mouth, and led us in prayer without performing ablution.
أنهم كانوا مع النبي ﷺ بالصهباء وهي على روحة من خيبر، فحضرت الصلاة، فدعا بطعام فلم يجده إلا سويقا، فلاك منه فلكناه معه، ثم دعا بماء فمضمض، ثم صلى وصلينا ولم يتوضأ.
Bukhari narrated it in the Book of Foods (5390) from Sulayman bin Harb, who said, Hammad narrated to us, from Yahya, from Bashir bin Yasar, from Suwayd bin Numan, and he mentioned it.His saying, "except sawiq," sawiq is a food made from crushed wheat and barley. A bedouin once described it, saying, "The traveler's provision, the food of the one in a hurry, and the sustenance of the sick." Fath al-Bari (1/312).I say, perhaps it is also made into a drink, as the following hadiths indicate.