How do we reconcile the ritual impurity (najāsa) of a small amount of water upon encountering impurity, with the purity of a garment if a small amount of water comes upon an impurity on it? And does the difference lie in the water coming upon the impurity?

The majority of scholars consider a small amount of water (less than two qullas) to become impure if an impurity falls into it. However, if water is poured over an impurity, it purifies it, even if the water is little. Ibn al-Arabi's statement supports this: "The arrival of an impurity upon water is not like the arrival of water upon an impurity." He cites the hadith, "When one of you wakes up from his sleep, he should not dip his hand into the vessel until he washes it three times," and the Prophet's command to pour water over the Bedouin's urine in the mosque.