The book contains two thousand four hundred & twenty five (2425) hadiths according to Maktaba Shamila. It is one of the oldest Musnad ( a kind of Hadith book) written.
It is written in first century of Islamic Calendar and written before the most authentic book of Hadiths (narrations of the Islamic prophet, Muhammad ﷺ) that are Sahihain (Sahih al-Bukhari & Sahih Muslim).
The Musnad (مسند) are collections of Hadiths which are classified by narrators, and therefore by Sahabas (companions of Muhammad). The books contain both Authentic and weak narrations.