the greatest punishment a parent can receive

Chazal tell us that because Avraham asked "Ba’meh eidah…," for a sign that his children would inherit Eretz Yisrael, he was punished with "Yado’a teida…," Hashem telling him that Bnei Yisrael would be enslaved in Egypt for four hundred years. The Kli Yakar uses some very harsh language – "haseichel yema’ain l’kabeil dersush zeh" -- in questioning what Chazal mean by this. If indeed Avraham sinned, asks the Kli Yakar, then why did not G-d punish him directly? Why lash out at future generations while letting Avraham himself off scott-free?

Afar ani tachas raglav of the Kli Yakar, but I don't see the question. The greatest pain you can cause to a parent is to bring harm to his/her children. Whatever punishment Hashem would have brought upon Avraham directly would have been easier for him to bear than hearing that his children would be enslaved for centuries. (Maybe you can read that into the Kli Yakar's answer, but it sounds to me like his point is that seeking knowledge can sometimes be a dangerous thing; G-d responded to Avraham's improper quest to know "ba'meh eidah"  by revealing "yado'a teidah," bad news that he would otherwise have kept hidden.)