Abu Dawud Book 35, Hadith Number 4686.

Narated By Umar ibn al-Khattab : Muslim ibn Yasar al-Juhani said: When Umar ibn al-Khattab was asked about the verse “When your Lord took their offspring from the backs of the children of Adam” – al-Qa’nabi recited the verse–he said: I heard the Apostle of Allah (PBUH) say when he was questioned about it: Allah created Adam, then passed His right hand over his back, and brought forth from it his offspring, saying: I have these for Paradise and these will do the deeds of those who go to Paradise. He then passed His hand over his back and brought forth from it his offspring, saying: I have created these for Hell, and they will do the deeds of those who go to Hell.

A man asked: What is the good of doing anything, Apostle of Allah? The Apostle of Allah (PBUH) said: When Allah creates a servant for Paradise, He employs him in doing the deeds of those who will go to Paradise, so that his final action before death is one of the deeds of those who go to Paradise, for which He will bring him into Paradise. But when He creates a servant for Hell, He employs him in doing the deeds of those who will go to Hell, so that his final action before death is one of the deeds of those who go to Hell, for which He will bring him into Hell.