Gibbs, Jeffrey A. “Matthew 7:7-12: Summary; Blessing and Calling." Matthew 1:1-11:1. St. Louis: Concordia Publishing House, 2006, pp. 376-382.
Gibbs considers Matthew 7:7-11 to represent a generous attitude of God. Here God shows a willingness to cre for His people, regardless of their failings (Gibbs 2006, 376). Though Jesus does teach persistence in prayer, that is not his purpose in this passage.
The structure of the Sermon on the Mount is normally a challenge. Gibbs considers Matthew 7:12 as "a summary for the whole large middle portion of the Sermon" (Gibbs 2006, 378). The main body of teaching is introduced in the Beatitudes. Here at the end, the blessing of God's mercy returns.
Verses 7-11, in Gibbs' estimation, does not focus on the disciples but points boldly to God's grace. Even if an earthly father is good, God is better (Gibbs 2006, 380).
The crux of the issue, in verse 12, is that the disciples are to treat all people, not just the disciples, as God would treat them (Gibbs 2006, 381). Gibbs quotes Luther at length, saying that all the things around us point to our ability and obligation to love and serve our neighbors (Gibbs 2006, 381-382).