Answer
The area between the navel and knee for a male is Satr (to be compulsorily
covered).
It is not permissible to have that area open in front of anyone besides the
wife. It is, therefore, advisable that the shorts cover the knees. It is
permissible but discouraged to recite the Qur’aan and make Dhikr while
wearing shorts that expose some part of the above knee.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai