In Genesis 15 God promises Abraham that his offspring will be afflicted for four hundred years. Frame makes the point (ST, p70) that "this promise and its fulfillment indicates that the blessing will come about through God alone, for only he controls history over such a great expanse of time."
I think it makes far greater claims about God than that. For this prophecy to be fulfilled, God has to work in the hearts and minds of countless individuals, numerous kings and rulers, many of whom are never in an obedient relationship with Him - and yet He is never thwarted.
In addition, it makes clear that God brings forth afflictions. Abraham's descendants would be afflicted for four hundred years. Why? Because God said so. Yet another proof that all afflictions and trials brought on to a believer in Christ are personally attended to by a Sovereign God Who has a perfect plan that will come to pass.
In the midst of each affliction, we are tested to ask, "is this God good?" The answer, of course, is the Cross.