Ат-Такасур 102:2

(Until ye come to the graves) this is because the Banu Sahm and Banu 'Abd Manaf were bragging to each other about which tribe is larger as concerns the number of its population, and found out that the Banu 'Abd Manaf were more numerous. The Banu Sahm said at that point: �We were rooted out by injustice in the pagan era; go and count the living and the dead of our people and the living and the dead of your people�. When they did so they found out that the Banu Sahm were more numerous. Therefore the above verses were revealed about them: bragging about status and lineage distracted you to the extent that you visited the graveyards to count the dead; it is also said that this means: increase in wealth and children distracts you until you die and be put in the graves.