This hadeeth comes under the following chapter: THE GROWTH OF A CHILD IN THE WOMB OF A MOTHER AND HIS DESTINY IN REGARD TO HIS LIVELIHOOD, HIS DEEDS, BOTH GOOD AND EVIL
Sahl b. Sa'd reported it from Allaah's Messenger (sallAllaahu alayhi wa sallam) that a person performs deeds like the deeds of the people of Paradise apparently before people and he would be amongst the dwellers of Hell and a person acts apparently like the people of Hell, but (in fact) he would be among the dwellers of Paradise.