What laughter pains the heart?
Rashi: Hashem jests with [Resha'im in this world, and their hearts will be pained in the world to come - "v'Atem Titz'aku mi'Ke'ev Lev" (Yeshayah 65:14).
Rashi (15): "Ki'Schok li'Chsil Asos Zimah" (10:23).
Malbim: Even if you see laughter on the Evvil's face, and he is succeeding, the heart is pained, for "Lev Yode'a Maras Nafsho" (9) - it senses that "Acharisah Tugah" - he goes in the path of death. Sechok is seen only externally; Simchah is in the heart. One can cry and laugh - he cries in his heart and laughs with his mouth, like R. Akiva (Avodah Zarah 20a 1 ).
Tosfos (Nedarim 50b DH Ishto): Turnusrufus' wife asked him to explain why he laughed and cried: This implies that he cried not only in his heart! (PF)
