This study deals with the grammatical expansion in the noble prophet Hadith, or discourse. Its problem was based on two aspects: - Grammarians studied expansion briefly and disagreed on its concept. Some of them confined it to deletion and disposal of sources and situations. While others added any deviation from authentic form to it, and others did not distinguish it from poetry imperatives. Indeed, rarely a grammarian devoted a chapter for grammatical expansion in his book, so it is usually scattered in researches, and some acknowledge the difficulty to encompass all its knowledge. 112 - Noble Hadith discourse contains issues that broke classic Arabic criteria. This compels some Arabic scholars to take care in relying on Hadith, fearing non-Arabs' influence on its recounting. So some question if it is possible to enlist Hadith in grammatical expansion that language allows, or was it affected by non-Arab language. This study aims to achieve the following objectives: To clarify grammatical expansion concept. To study grammatical expansion based on Hadith blog that from the era before putting grammatical rules. - To study phenomena of grammatical expansion as used in Hadiths of Imam Ahmed book and grammarians' views on the same. The study attempted to reach it objectives through one theoretical chapter and two applied ones as follows: Chapter (1): concept of grammatical expansion. Chapter (2): grammatical expansion in individual words. Chapter (3): grammatical expansion in structures. The study is concluded by many results most important are the understanding that the grammatical expansion is a lingual usage where a word from one entry or category took the function of a word from another entry of category, or went beyond the rule as option to expand speech. So Hadith discourse's departure from standard criteria may be enlisted as aspects of expansion that Arabic language allowed, especially what usage saw in readings, poetry and Arabic accents.