Heidegger's Bible Handbook: 1 Samuel: Its Title
1. The names of the book. Samuel, θεόκλητος/theokletos, asked of God.
The two books of שמואל/Samuel, or θεοκλήτου/theokletou, asked of God, as Origen, in Eusebius, calls him, were given their name from Samuel himself, whose rise and government, in the first place, they set forth, by reason of the passage in 1 Chronicles 29:29, in which the acts of David, first and last, are said to have been written עַל־דִּבְרֵי֙ שְׁמוּאֵ֣ל, in the words of Samuel. By the Septuagint Translators the Books are called Βασιλέων/Kings, or Βασιλειῶν/ Kingdoms; by the Vulgate, Regum/Kings; by Jerome, Regnorum/Kingdoms.
 See 1 Samuel 1:20: “Wherefore it came to pass, when the time was come about after Hannah had conceived, that she bare a son, and called his name Samuel (שְׁמוּאֵל), saying, Because I have asked him (שְׁאִלְתִּיו) of the Lord.”  1 Chronicles 29:29: “Now the acts of David the king, first and last, behold, they are written in the book of Samuel the seer, and in the book of Nathan the prophet, and in the book of Gad the seer (עַל־דִּבְרֵי֙ שְׁמוּאֵ֣ל הָרֹאֶ֔ה וְעַל־דִּבְרֵי֙ נָתָ֣ן הַנָּבִ֔יא וְעַל־דִּבְרֵ֖י גָּ֥ד הַחֹזֶֽה׃)…”