The first verse of this chapter tells us that there is both consonance and dissonance between Abraham and Isaac. As his son takes the stage there is a famine, not the same famine, but a famine just as there was in the days of his father. We are to distinguish yet remember.
Abraham would face two famines, Isaac one. God would allow Abraham to sin in self-reliance by going to Egypt, He would prevent Isaac from sinning. With Abraham He would protect the covenant using the miraculous, both plagues (Genesis 12:17) and a dream (Genesis 20:6), whereas with Isaac subtle providence would be his tool (Genesis 26:8). Still it is the same covenant, the same promises, the same faithfulness, the same God who permeates both of their lives.
God’s mysterious ways and methods may be different, he may sovereignly order circumstances in a different way, but His covenant faithfulness is unchanging. Do not look to circumstances as a gauge of God’s faithfulness, look to His covenant, look to His Christ. God will be with Isaac exactly as He was with Abraham (Genesis 26:3) exactly as He will be with you.
Addendum: Last night I mentioned how Genesis 26:12-17 is a favorite passage for proponents of the “prosperity gospel”. Al Mohler has written a post reflecting upon the life of Oral Roberts. Concerning the prosperity gospel he writes:
Prosperity theology teaches that God promises his people financial gain and bodily health. It is a false Gospel that turns the Gospel of Christ upside-down. The true Gospel offers forgiveness of sins and leads to a life of discipleship. Following Christ demands poverty more often than wealth, and we are not promised relief from physical ills, injury, sickness, or death. Christians die along with all other mortals, but we are promised the gift of eternal life in Christ.