Again, not exactly a song, but some wisdom concerning the Next World according to the Talmud, Tractate Pirkei Avot (Wisdom of the Fathers).
Pirkie Avot 4:21-22
21. Rabbi Jacob used to say: This world is like a hallway to the future world. Prepare yourself in the hallway that you may enter into the banquet hall.
22. He also would say: Better is one hour of penitence and good deeds in this world than all the life of the world to come. Better is one hour of spiritual repose in the world to come than all the life of this world.