dition of history writing, with some signs of influence Ephorus as well.
Witherington, op. cit., page 33-34.
At the very least, therefore, Luke was aware of and shows an interest in following the example of historians who favored as accurate as possible speech recording. While standing alone these similarities do not show that Luke followed their example, combined with Section A above and Sections C and D below, it is probative evidence that he intended to do so.
C.     Luke's Style of Writing in Acts
Some have objected that the language of the speeches is too Lukan in style to reflect anyone else's words. Moreover, some have argued that the speeches of Peter and Paul are too much alike, and that especially Paul's are too distinct from his letters to reflect a true Pauline source. However, even in the Gospel of Luke, where Luke indisputably relies faithfully on pre-existing sources, Luke polishes the Greek and writes in a consistently Lukan style. Indeed, without the Gospels of Matthew and Mark, it would be difficult to have detected that Luke was using pre-existing sources or determine their boundaries even if we did. Moreover, no one suggests that Luke is providing us with verbatim transcripts of what was said. Accordingly, this objection has little merit.
Furthermore, most of the speeches attributed to Peter and Paul in Acts were directed to pagan or Jewish audiences, whereas the canonical letters that bear their names were directed to Christians. All of the undisputed Paulines were addressed either to churches or to an individual who was already a Christian. Therefore, the audiences were different. The context was different. And the purpose was different. So, we should not expect them to be remarkably similar.
D.     Several Speeches in Acts Are NonLukan and Correspond with External Sources
Despite Luke's quality Greek and the different contexts, he recites four important speeches that demonstrate marks of relying on pre-existing non-Lukan materials.
1.     Stephen's Speech Prior to His Martyrdom
The speech of Stephen (Acts 7), the first recorded Christian martyr, is the longest speech in Acts. In Acts 6, Luke informs us that Stephen was an important member of the Jerusalem Church. He began preaching in Jerusalem and so incited some of his opponents, that they seized Stephen and brought him before the Council. Confronted by the Council, Stephen spoke at length about the history of Israel and the coming of Christ. He closed is speech with, "Behold, I see the heavens opened, and the Son of man standing at the right hand of God." 7:56. After the speech, Stephen was stoned to death by an enraged mob.
A notable characteristic about Stephen's speech is that it is "not noticeably Lukan in character." Witherington, op. cit., page 265. Indeed, after studying the language and theology of Stephen's speech as compared with the rest of Luke's writings, "[m]ost scholars  rightly recognize Luke drawing on some sort of source here. Ibid. I. Howard Marshall agrees. He describes as a "certainty" that Luke used preexisting source material for Stephen's speech in Acts 7. Luke: Historian and Theologian, page 72. "[T]he speech of Stephen has by no means been fully assimilated to Lucan ideas but retains several individual characteristics." Ibid. For example, in Acts 7:46-49, Stephen's speech is critical of even the idea of the Temple. But in Luke 1:8-23; 24-53; Acts 3:1 and elsewhere, Luke seems to be more positive about it. "For Stephen the idea of a fixed structure for the worship of God was misguided from the beginning; for Luke the temple is the house of God throughout the twofold work until the moment when Paul is ejected from the sacred precincts." F.F. Bruce, The Acts of the Apostles, pages 38-39.
In sum, the longest speech in Acts displays remarkably unLukan characteristics which have lead the majority of New Testament scholars to the conclusion that Luke has based Acts 7 on a preexisting source. Just as with the Markan and Q material, Luke has relied on an already established tradition here.
2.     Peter's Speech to the Jews in Je