Jesus taught the Apostles in Jerusalem, or more specifically on the Mount of Olives how to pray (Luke 11:1-4). Matthew, also, has Jesus teach a similar prayer to his disciples in Galilee near the beginning of his public ministry. In Matthew’s narrative Jesus teaches the Apostles on a mountain probably near Capernaum during what is called the Sermon on the Mount (Matthew 6:9-13). Matthew places the context of Jesus’ prayer over against the ‘hypocrisy’ of those who love to be seen praying in public(Matthew 6:5-7). On the other hand, Luke has Jesus teach the Apostles this prayer, while they were in Judea celebrating the Passover. The context there was ignorance. The disciples came to Jesus in Luke, while Jesus called his disciples to him in Matthew.
Some may ask, are Matthew and Luke taking what Jesus said and placing it in a context of their choosing, or did Jesus repeat himself on different occasions? Apparently, Jesus taught similar things at different times and under different circumstances. We often do this ourselves with our children. At one time we might teach our child to have integrity and not lie as his or her friends do. On a different occasion, we might teach our child to have integrity and not cheat in a game he or she is playing, the same idea, but under different contexts.
In Luke Jesus began to teach his disciples by saying, “When you pray say, ‘our Father…” (Luke 11:2). What decent father is unwilling to care for his child? What child would feel uncomfortable in the presence of his father? Does a child need a formula to extract a favor from his own father? Immediately, Jesus places the context of praying in a very favorable atmosphere. The question should not be, how can I get God to do as I ask, but why wouldn’t my Father want to do as I ask?
Although the concept of God being as a father is found in the Old Testament (Deuteronomy 1:31; 32:6; Psalms 68:5; 103:13; Isaiah 1:2; 63:8, 16; 64:8; Jeremiah 3:4, 19; 31:9; Hosea 11:1; Malachi 3:1), he was never addressed as Father there. Addressing God as Father is a new concept taught by Jesus. Moreover, since Jesus probably taught in Aramaic, when he told his disciples to address God as “our Father” he was really telling them to address him as “Abba” or in modern Western vernacular, Daddy (Luke 11:2; cf. Mark 14:36; Romans 8:15; Galatians 4:6; 1Peter 1:17), a very familiar term, perhaps irreverent in some social circles.
By telling his disciples to enter into the presence of God by addressing him as “Abba” (Daddy), he was telling them to understand their relationship with God to be a very familiar one, a familial relationship, whereby it would be a common ordinary thing for them to speak to God, their Father.
The Jewish authorities didn’t appreciate how Jesus addressed God and saw it as an attempt by him to be seen as equal with God (cf. John 5:18). The Jewish authorities had the idea that God was far off and needed to be entreated, but Jesus revealed God as Father, someone close who needs no special appeals to grant the requests of his children.
 “God was never addressed as Father in the Old Testament. When God is called Father in the Psalms, it is by way of comparison. Earthly fatherhood is taken as the model to which God is compared. For example, David sings: ‘A father to the fatherless, a defender of widows, is God in his holy dwelling.’ …He indicated that God is The Father, and earthly fatherhood is modeled upon the heavenly reality. God is not like an earthly father, He is the original!” – John Schultz The Gospel of Luke; page 141-142.