Is there any problem to lengthen the nails?
Cutting nails is a sunnah and a neccesarity of being human. Our Messenger appoints that one from the five sunnah’s related to the cleanliness is cutting nails.
When the nails lengthen, microbes and germs enter between nail and meat. Especially hand fingers touch everywhere and the mouth too during the eating, trasmitting the germs and infecting these places. During ablution and body ablution-gusl-the water must reach in the place between the nail and the meat in the top of the finger-in the place where the nail lengthen-. If there is dirt there and the water does not reach, the ablution will be not completed. If the nail will be clean, too, it is not fair to lengthen it much, because this is in contrary with Sunnah.