Praise be to Allaah.
The outside of a thick beard should be washed, but it is not a must to
wash the inside or the skin underneath. However, it is encouraged to run one's fingers
through the beard. Al-Nawawi (may Allaah have mercy on him) said: The scholars agree
unanimously that a thick beard should be washed, but that the inner layers do not need to
be washed, nor does the skin underneath. This is the opinion of the majority of scholars
among the Sahaabah, Taabieen and those who came after them. Ibn Rushd said:
This is an issue in which I know of no difference of opinion.
However, if the beard is thin and the skin underneath is visible, then it
should be washed thoroughly when performing wudoo.