Luke 2.40-52 and 1 Samuel 2-3
Luke 2.40 and 2.52 act as bookends to the story of Jesus' childhood experience in the temple. At the age of twelve, Jesus accompanied his parents on their customary annual journey (2.42) to Passover. Upon returning to their hometown, Jesus' parents noticed his absence, and turned back to Jerusalem to find him in the temple with the Jewish teachers, who were astonished at his questions and answers.
Why does Luke (alone) include this single detail of Jesus' childhood? If he, with his family, made the trip every year, what made this particular year significant, or at least worth mentioning? There a couple of reasons why Luke's audience, Theophilus the high priest of 37-41 CE, might have found the story significant.
Theophilus was the son of Annas, high priest from 8-15 CE. Annas would have been the high priest during the twelve-year-old Jesus' visit. Theophilus would perhaps have been familiar with the story from his own childhood. The fact that "all who heard him were amazed at his understanding and his answers" (2.47) might have resonated with Theophilus.
Secondly, Luke 2.40-52 is a strong parallel to 1 Samuel 2-3. Luke three times mentions the “growth” of a child: 1.80, of young John the Baptist; 2.40 and 2.52, of young Jesus. Between the latter two we find the story of Jesus in the temple. There are three such comments in 1 Samuel 2-3 as well: 2.21; 2.26; 3.19, all concerning young Samuel. Between the latter two we find a detail of the corruption of the priesthood and God’s plan to make adjustments. Is Luke suggesting that the priesthood of Jesus' day was corrupt just as the priesthood of Samuel's day? Perhaps…
Like Jesus' family, little Samuel's family was accustomed to making an annual trek to make sacrifice (1 Samuel 2.19; see also 1.3, 21). Though the text of 1 Samuel does not give Samuel’s age, Jewish historian Josephus has somehow come to conclude he was twelve at the time of God's calling him to prophesy (Ant. 5.10.4).
A cursory read of the story of 1 Samuel 2-3 will reveal a striking parallel to Luke's story:
After the "growth" comment in 2.26, the writer details why God has turned against the priesthood, blaming Eli’s sons, Hophni and Phinehas (2.12ff.). God promised that they would drop dead, and that he would raise up a faithful priest. (2.34-35). The passage contains four references to "your father’s house" (2.27, 28, 30, 31). Samuel's mother had made for him a "linen ephod" to wear on the annual trips to sacrifice (2.18). This is one of God’s requirements of the priests when "going before [him]" (2.28). Eli had favored his sons more than God (3.29). So, God promised to remove Eli's sons and place his own priest in charge. From 3.1-18, we get the idea that Samuel fits the requirements God had established for the priests, thus seemingly fulfilling the promise to "raise up for myself a faithful high priest"(2.35). Though Samuel did not serve as a priest proper, he did perform many of the priestly duties.
Luke has shown the corruption of the priesthood in Theophilus' day, using the family members of Theophilus as examples of such corruption. Jesus' outstanding character before the teachers in the temple demonstrate that God's hand is upon him, that just as young Samuel was called by God for service so God was calling young Jesus. Jesus' question to his parents upon their finding him was, "Did you not know that I must be in my father’s house?" (Luke 2.49, emphasis added). Perhaps this is an allusion to God's fulfilling his promise to raise up a faithful priest in "a sure house", "your father's house" (1 Samuel 2.30, 35, emphasis added).
I suspect that Luke told the story of Jesus' childhood to establish to Theophilus that Jesus is the eschatological [high] priest, fulfilling the promise God made in 1 Samuel 2. Luke has subtly pointed to data personal to Theophilus (such as Annas' witness of the twelve-year-old Jesus) to prove his case. The story of Eli's sons is perhaps the best known story of the Jewish priesthood's corruption. For Luke to parallel Jesus' childhood experience to that of Samuel's in a context where the corrupt priesthood is specifically targeted by God, who promised to raise up a faithful priest for his house, would have given his story special leverage, being addressed to a certain high priest.
Four extra tidbits which might help establish a relationship between Luke and 1 Samuel:
1. Hannah, Samuel's mother, after Samuel was born, exalted God (1 Samuel 2.1-10). When Mary visited Elizabeth to share her good news, Mary magnified the Lord in similar fashion (Luke 1.46-55). Just as in Samuel's story Hannah's prayer precedes the story of Samuel's boyhood experience, so also in Luke's story Mary's prayer precedes the childhood experience of Jesus. If Luke were drawing attention by was of parallel, this is yet another indicator to his that he is doing so.
2. There is in both a comment that "this shall be a sign unto you" in close proximity to the stories in question (1 Samuel 2.34; Luke 2.12).
3. There is a formulaic "X blessed X" found in both contexts (1 Samuel 2.20; Luke 2.34).
4. In 1 Samuel 2.36, God says that the destitute will come to his faithful priest begging for a piece of silver or a morsel of bread. Perhaps passages such as Luke 14.1-24; 15.8, 17 (as a negative correlation) mean to fulfill this in some way.
 There is also a slight parallel of Luke's comment about Jesus' growth with that of a young Moses in Jos. Ant. 2.9.6[228-231].
 See my post: http://ltdahn-stluke.blogspot.com/2006/11/identifying-theophilus.html.