The Awrah should be covered with something that is permissible to use and should not be transparent that one’s skin color can be seen.

Regarding the Awrah for men:

• The Awarh for boys between 7-10 years of age is the private parts.
• The Awrah for males 10 years of age and older and girls before the age of maturity, is what between the navel and the knees.

Regarding the Awrah for women, there are three opinions:

• The entire body except the face (the Hanbalis).
• The entire body except the face and the hands (the Malikes and the Shafe’es).
• The entire body except the face, the hands and the feet (the Hanafe’es).

If one can finds nothing to cover his Awrah except a Najis clothes, he should pray in it. If one can find nothing to cover his Awrah he may pray with his Awrah uncovered. 

Note: If, non intentionally, a small part of the Awarah is uncovered during the Salah, or a large part of the Awrah is uncovered for a small period of time, the Salah is valid.