Is prayer valid if the prayer spot is on ground that was previously impure, but has since dried, or if something pure is spread upon it?

Primary text

Prayer is valid, though disliked (makruh), if performed on ground that was impure provided the impurity has dried, or if a pure material is spread over the spot. This is the apparent position of Ahmad ibn Hanbal, and it is the view of Tawus, Malik, al-Awza'i, al-Shafi'i, and Ishaq. The validity rests on the principle that purity is required for the worshipper's body, clothing, and the immediate place of prayer, all of which are met in this situation. The objection that the ground is a burial place for impurity, like a graveyard, is not accepted because prayer in actual graves is invalid even if those graves are not inherently impure places, suggesting the ruling is not universally derived from the mere presence of impurity.