God has chosen certain acts for all of His Prophets and their followers to perform. These acts, are known as sunan al-fitra (acts required by human nature), are as follows:
Circumcision
This prevents dirt from getting on one's penis and also makes it easy to keep clean. The Shafi'i scholars maintain that it should be done on the seventh day, although it is permissible to do it later.
Impure Hair
Shaving pubic hairs and pulling out underarm hairs. Doing so is sunna. However, it is enough to trim or pull it out.
Personal Grooming
Clipping fingernails, trimming and shaving the moustache , and keeping the beard tidy. Abu Hurayra reported that the Messenger of God, upon whom be God's blessings and peace, said, "Five things are part of one's fitra: Shaving the pubic hair, circumcision, trimming the moustache, removing any underarm hair, and trimming the nails." (Muslim, "Tahara," 49) A moustache should not be so long that food particles, drink, and dirt accumulate in it. If one grows a beard, it should not be untidy.
Honoring and combing one's hair.Abu Hurayra reported that the Prophet, upon whom be peace, said: "Whoever has hair should honor it" (Abu Dawud, "Tarajjul," 3:4163). Cutting one's hair off is permissible, and so is letting it grow if one honors it.
Leaving gray hairs
Leaving gray hairs in place.This applies to both men and women. 'Amr ibn Shu'ayb related, on the authority of his father from his grandfather, that the Messenger, upon him be peace and blessings, said: "Do not pluck the gray hairs, as they are a Muslim's light. A Muslim never grows gray in Islam except that God writes for him, due to that, a good deed, raises him a degree, and erases for him, due to that, one of his sins" (Ibn Hanbal, 2:179; Tirmidhi, "Adab," 56).
Dyeing one's gray hair.According to the accepted opini on, dyeing one's gray hair by using henna, red dye, yellow dye, and so on is permissible, provided that the dyes are religiously allowable.
Using perfume
Using musk and other perfumes that are free of alcohol and similar forbidden things is highly advisable, for they are pleasing to the soul and beautify the atmosphere.
