Is the prayer valid if the prayer mat (mandil) has one impure edge or if the prayer spot is connected to impurity by a taut rope?
Chapter on Praying with Impurity and Other Matters
Al-Mughni
Book of Prayer
Primary text
The prayer is valid if the object used for prayer (musalla) is pure, even if it is connected to an impurity via a taut rope beneath the feet, regardless of whether the impurity moves with the person's movement or remains stationary. This is because the worshipper is neither physically carrying the impurity nor praying directly upon it; rather, his prayer spot is merely contiguous with it, analogous to praying on pure ground connected to impure ground.
Supporting text
Some scholars among our school hold that if the impurity moves due to the worshipper's movement, the prayer is invalid. However, the definitive ruling relies on the first stated position.