Midrash su Geremia 31:13

Then sang Moses. At times the word then refers to events that happened in the past, and at other times it refers to events that are to transpire in the future. The word then refers to past events in the following verses: Then began man to call upon the name of the Lord (Gen. 4:26), Then she said: “A bridegroom of blood” (Exod. 4:26), Then sang Israel this song (Num. 21:17), Then Solomon spoke (I Kings 18:12). All of these refer to past events. Instances in which the word then alludes to future events are: Then thou shalt see (Isa. 60:5), Then shall thy light break forth (ibid. 58:8), Then shall the lame man leap as a hart (ibid. 35:6), Then the eyes of the blind shall be opened (ibid., v. 5), Then shall the virgin rejoice (Jer. 31:13), Then was our mouth filled with laughter, and our tongue with singing (Ps. 126:2), and Then said they among the nations (ibid.). All these allude to future events. From this we learn that the concept of the resurrection of the dead is derived from the Torah.

“To whom the word of the Lord came… until the end of eleven years of Zedekiah son of Josiah, king of Judah, until the exile of Jerusalem in the fifth month.” (Jeremiah 1:2-3) R’ Avon said: the lion (ari) came up during the constellation of the lion and destroyed Ariel. ‘The lion came up’ refers to Nebuchadnezzar the wicked, as it is written “A lion has come up from his thicket…” (Jeremiah 4:7) ‘In the constellation of the lion’, “…until the exile of Jerusalem in the fifth month.” (Jeremiah 1:3) ‘And destroyed Ariel’, “Woe, Ariel, Ariel, the city wherein David encamped!” (Isaiah 29:1) This happened in order that the lion would come in the constellation of the lion and rebuild Ariel. ‘The lion would come’ refers to the Holy One, as it is written “A lion has roared; who will not fear?” (Amos 3:8) ‘In the constellation of the lion’, “…and I will turn their mourning into joy…” (Jeremiah 31:12) ‘And rebuild Ariel’, “The Lord is the builder of Jerusalem; He will gather the outcasts of Israel.” (Psalms 147:2)

The Holy One, blessed be He, said: In this world you grieved for this righteous man for seven days, but in the world-to-come I will turn their mourning into joy, and will comfort them, and make them rejoice from their sorrow (Jer. 31:13). And I will comfort Zion and its vast places, as it is said: For the Lord hath comforted Zion; He hath comforted all her waste places and hath made her wilderness like Eden, and her desert like the garden of the Lord; joy and gladness shall be found therein, thanksgiving and the voice of melody (Isa. 51:3).