Moosaa Richardson provides examples of scholars approaching 90 and 100 years of age, still sharp in their faculties and healthy. From a class in explanation of the hadeeth (which means), "Preserve [the Limits of] Allah, and He will preserve you," which is #19 of the 40 Hadeeth, as recorded originally at al-Masjid al-Awwal (the First Muslim Mosque) of Pittsburgh, Pennsylvania (USA) on 1437.12.23.