"Scholars have compiled forty hadeeth on faith and belief (usool), on practical matters (furoo), on jihaad, on austerity (zuhd), on etiquette (adaab), and even on sermons (khutbahs). All of these (collections) were concerning righteous aims. May Allaah be pleased with those who sought them. However I have found it best to collect together forty hadeeth which are more important than all of those. These forty hadeeth incorporate all of those separate topics. In fact, each hadeeth is by itself a great general precept from the foundations of the Religion. Some scholars state that all of Islaam revolves around these hadeeth. Some have said, about a particular hadeeth, that they are one-half of Islaam, one third of Islaam and so forth."