Midrash su Zaccaria 8:6

What is the cause for the above mentioned mourning? R. Dosa and the Rabbis differ: One gives the reason that it [the mourning] is for the Messiah, the son of Joseph, who is to be killed; and the other gives the reason that it is for the evil inclination, which is to be killed. It is quite comprehensible according to the one who holds that it will be for the Messiah, the son of Joseph, as is said (Zech. 12, 10) And they will look up toward me [for every one] whom they have trust through, and they will lament for him, as one lamenteth for an only son, and weep bitterly for him, as one weepeth bitterly for the first-born; but ing to the one who holds that it is to be be for the death of the evil inclination, why mourn? On the contrary, it should be cause for rejoicing! This could be interpreted by the lecture of R. Juda b. Layi who said: "In the future the Holy One, praised be He! will bring the evil angel and slaughter him in the presence of both the upright and the wicked. To the former he will appear like a high mountain, and to the latter he will appear like a thin hair. Both, however, will cry. The upright will cry, saying: 'How could we have overpowered such a high mountain?' and the wicked will cry, saying: 'How could we not have subdued such a thin hair?' And the Holy One, praised be He! will also join them in wondering, as it is said (Zech. 8, 6) Thus hath said the Lord of hosts: If it should be marvellous in the eyes of the remnant of this people in those days, it should also be marvellous in My eyes." R. Assis said: "In the beginning, the evil inclination appears insignificant and thin as a cobweb, and finally he becomes as thick as a wagon-rope, as it is said (Is. 5, 18) Woe unto those that draw iniquity with the cords of falsehood, and as with a wagon-rope, sinfulness."