Praise be to Allah.
Al-matn (text) in Arabic means the back. In Islamic terminology it refers to the contents of a book, such as the text of Saheeh al-Bukhaari or the text of Zaad al-Mustaqni’.
The scholars usually use this word to refer to brief books that are in circulation among the scholars and seekers of knowledge in a particular field of knowledge. For example, in the case of ‘aqeedah (tenets of faith), they may say Matn al-Waasitiyyah, referring to the brief book on ‘aqeedah by Shaykh al-Islam Ibn Taymiyah, which is called al-‘Aqeedah al-Waasitiyyah. Similarly, Matn al-Tahhaawiyyah refers to a brief book on ‘aqeedah by Imam al-Tahhaawi.
Usually what is meant by the word matn (text) is to distinguish the book from its commentary. For example they may say Matn al-Tahhaawiyyah to distinguish it from Sharh al-Tahhaawiyyah (the commentary on al-Tahhaawiyyah), which is another book in which Ibn Abi’l-‘Izz al-Hanafi commented on the original short book, al-‘Aqeedah al-Tahhaawiyyah.
Mutoon (pl. of matn) or texts are usually short but contain many meanings and important principles of knowledge which are written about in brief terms to make it easy to memorize them and focus on issues of knowledge. Imam al-Bukhaari (may Allaah have mercy on him) said: al-Khaleel ibn Ahmad said: Words may be made brief in order to memorize them and made long in order to understand. Khalq Af’aal al-‘Ibaad, no. 244.
And Allaah knows best.