Fath al-Rabbani

Benefits: … Without any doubt, the cat is among the animals that are forbidden (haram), but from these narrations it is understood that its leftover (saliva) is pure. The command of Allah, the Exalted, is: {طَوَّافُوْنَ عَلَیْکُمْ بَعْضُکُمْ عَلٰی بَعْضٍ} … "You all are frequent visitors to one another." (Surah An-Nur: 58) Servants and masters often need to meet each other at all times; in view of this general necessity, Allah, the Exalted, has granted slaves in this verse the permission to come to their masters without seeking permission, except during three specific times. The case of the cat is exactly the same: its temperament is such that it frequently comes and goes inside the house, and even at night it sneaks into the beds of the household members. It also has the habit that, as much as it is able, it gets into the utensils. Therefore, just as with slaves, the Shari‘ah has granted a concession for it as well, and has declared its leftover (saliva) to be pure. Furthermore, in accordance with the requirements of this concession, this animal has been made clean by nature; for example, after eating something, it rubs its mouth on the ground, and it is in its nature to cover its filth with its paws by throwing soil over it.