Al-Habb is used generically for grain inside the spike or the sheath. The term is used particularly to denote crops belonging to the grass family, like wheat, barley, corn, rice, and oats, which are grown for their grains, a main nutrition source. The individual grains are small, with one seed, whose coat merges with the fruit wall. The grain is known to botanists as caryopsis. Carbohydrates, especially starch, form most of the grain. Each grain contains a minute embryo, which develops into a seedling.
The word Habb and its derivatives are mentioned 12 times in the Holy Qur’an. Allah, the Most Sublime, says: “Verily, it is Allah who causes the seed-grain and the date stone to split and sprout. He brings forth the living from the dead, and it is he who brings forth the dead from the living. such is Allah: then how are we deluded away from the truth?” Surat Al-Anaam, verse 95
Narrated Abu Hazim: Sahl said, "We used to feel happy on Fridays." I asked Sahl, "Why?" He said, "There was an old woman of our acquaintance who used to send somebody to Buda'a (Ibn Maslama said, "Buda'a was a garden of date-palms at Medina). She used to pull out the silq (a kind of vegetable) from its roots and put it in a cooking pot, adding some powdered barley over it (and cook it). After finishing the Jumua (Friday) prayer we used to (pass by her and) greet her, whereupon she would present us with that meal, so we used to feel happy because of that. We used to have neither a midday nap, nor meals, except after the Friday prayer." Sahih Al Bukhari, book of Asking Permission
ElGharib, A. E.; Botanical terms in the Holy Qur'an and Hadith "Habb". Qatar Foundation’s Fortnightly newspaper, issue 104, Thursday 20 February 2014.