Books of Samuel

The Books of Samuel (Hebrew: Sefer Sh'muel ספר שמואל), are part of the Tanakh (part of Judaism's Hebrew Bible) and also of the Old Testament (of Christianity). The work was originally written in Hebrew, and the Book(s) of Samuel originally formed a single text, as they are often considered today in Hebrew bibles.
See more at Wikipedia.org...

The LXX. translators regarded the books of Samuel and of Kings as forming one continuous history, which they divided into four books, which they called "Books of the Kingdom." The Vulgate version followed this division, but styled them "Books of the Kings." These books of Samuel they accordingly called the "First" and "Second" Books of Kings, and not, as in the modern Protestant versions, the "First" and "Second" Books of Samuel. The authors of the books of Samuel were probably Samuel, Gad, and Nathan. Samuel penned the first twenty-four chapters of the first book. Gad, the companion of David (1 Sam. 22:5), continued the history thus commenced; and Nathan completed it, probably arranging the whole in the form in which we now have it (1 Chr. 29:29). The contents of the books. The first book comprises a period of about a hundred years, and nearly coincides with the life of Samuel. It contains (1) the history of Eli (1-4); (2) the history of Samuel (5-12); (3) the history of Saul, and of David in exile (13-31). The second book, comprising a period of perhaps fifty years, contains a history of the reign of David (1) over Judah (1-4), and (2) over all Israel (5-24), mainly in its political aspects. The last four chapters of Second Samuel may be regarded as a sort of appendix recording various events, but not chronologically. These books do not contain complete histories. Frequent gaps are met with in the record, because their object is to present a history of the kingdom of God in its gradual development, and not of the events of the reigns of the successive rulers. It is noticeable that the section (2 Sam. 11:2-12: 29) containing an account of David's sin in the matter of Bathsheba is omitted in the corresponding passage in 1 Chr. 20.