Zecharia 12:10-12

וְהִבִּיטוּ אֵלַי, אֵת אֲשֶׁר-דָּקָרוּ; וְסָפְדוּ עָלָיו, כְּמִסְפֵּד עַל-הַיָּחִיד, וְהָמֵר עָלָיו, כְּהָמֵר עַל-הַבְּכוֹר. בַּיּוֹם הַהוּא, יִגְדַּל הַמִּסְפֵּד בִּירוּשָׁלִַם, כְּמִסְפַּד הֲדַדְרִמּוֹן, בְּבִקְעַת מְגִדּוֹן .וְסָפְדָה הָאָרֶץ, מִשְׁפָּחוֹת מִשְׁפָּחוֹת לְבָד

“And they shall look unto Me because they have thrust him through; and they shall mourn for him, as one mourns for his only son, and shall be in bitterness for him, as one that is in bitterness for his first-born. In that day shall there be a great mourning in Yerushalayim, as the mourning of Hadadrimmon in the valley of Megiddon. And the land shall mourn, every family apart.”

The pesukim here describe a great mourning that will take place in the future, but do not reveal what the people will mourn for. The Gemara in Sukkah 52a brings a machlokes (disagreement); one opinion says they are will mourn over Moshiach ben Yosef, but the other opinion posits they will mourn because Hashem killed the yetzer hora. The Gemara asks the obvious question; why is the destruction of the yetzer hora a reason to mourn and not a reason for joy? The Gemara brings an answer from R’ Yehuda who says that “In the future, Hashem, will slaughter the yetzer hora; to the righteous it will look like a great mountain, to the wicked it will look like a thread of hair, and both groups will be crying. The righteous will cry and say, ‘How were we able to conquer a great mountain like this?’, and the wicked will cry and say, ‘Why were we not able to conquer a thread of hair like this?’”

Why did the righteous see one thing and the wicked another? What does this mean?

The Bais Halevi on Bereishis explains as follows. The yetzer hora entices us to sin by exaggerating the pleasure of a sin, but once we sin, we see how little pleasure the sin really offers us. There is a big disparity between the pleasure people are tempted with and think they will receive, and what they actually receive when they succumb. So when the righteous walk away from temptation they are walking away from the imaginary pleasure the wicked will never receive.

For this reason, when the righteous person looks at the yetzer hora in the future and perceives what he overcame, he will weep in shock and amazement at the great mountain of imaginary pleasure he managed to forgo. But when the wicked person looks at what he actually received and what he sold himself for, he will weep with remorse at being tricked and receiving merely a ‘hairs thread’ of satisfaction for his sins.