What are the methods for removing impurities (najāsa)? Does it disappear with the passage of time or by exposure to the sun and air? Do small drops of water renew the impurity of a shoe?

According to the majority of scholars, najasah (definition) (impurity) is removed by water, whereas the Hanafis and Sheikh Al-Islam Ibn Taymiyyah hold that it can be removed by any liquid that eliminates it. Impurity on the ground is purified by dryness according to the Hanafis and Ibn Taymiyyah, while smooth surfaces are purified by wiping. Impurities are also purified by transformation (istihalah) according to many scholars, which is also the chosen view of Ibn Taymiyyah. The removal of najasah is obligatory only for prayer, and a small amount of impurity is excused by many scholars. The original ruling for anything doubtful is purity. As for footwear, it is not purified by dryness, but rather by pouring water over it; the passage of time does not purify it. The sole of a shoe can be purified by rubbing it on the ground according to some scholars.