Yitzchak's Tefilla & Unintended Consequences.
וַיֵּעָתֶר לוֹ ה' וַתַּהַר רִבְקָה אִשְׁתּוֹ.
"We see that it is possible for a tefilla to be answered even when, unbeknown st to the mispallel, the desired answer is ultimately injurious. The one who is praying knows nothing about the collateral effect of the answer to his tefilla. He is only doing what the Torah teaches- when you need something, pray. But if he davens well enough and hard enough and long enough, sometimes the tefilla is answered as he desires, and this sets into motion a cascade of unintended and unexpected and unwanted consequences.
It's like Robert Merton's law of unintended consequences. a widely quoted admonition that intervention in a complex system always creates unanticipated and often undesirable outcomes. Does this sound reasonable to you?" (Havolim)