The World Federation One Stop Fiqh

Ruling 188

If the sun shines on one side of an impure wall and as a result the other side of the wall – on which the sun did not shine – also becomes dry, it is not farfetched (baʿīd)23 to consider both sides as having become pure [i.e. both sides are deemed to be pure]. However, if one day the sun dries the exterior of a wall or some earth and another day its interior, then only its exterior becomes pure.

23 For practical purposes, a legal opinion that is termed ‘not farfetched’ equates to a fatwa.