I would like to provide a very brief summary of the basic rulings related to the purity of dogs, keeping dogs, and keeping dogs inside the house.
There is disagreement concerning the purity of dogs and their saliva. Numerous ḥadīths2mention that if a dog licks from one’s bowl, its contents need to be thrown out and the bowl must be washed seven times with water – using soil in one of the washings. Scholars differ in their understanding of these ḥadīths and other evidence related to this issue, leading to disagreement over whether dogs or their saliva are pure, and whether things touched by dogs need to be cleaned in a particular way. Ḥanafīs consider dogs to be pure, but their slobber filthy. Mālikīs consider dogs and their slobber to be pure. Shāfiʿīs and Ḥanbalīs consider dogs and their slobber to be filthy.3
There is general agreement amongst the scholars that we are discouraged from keeping dogs, and that we should not keep dogs without need to do so. This is due to the many ḥadīths that mention that anyone who keeps a dog will lose rewards for each day he keeps it, unless the dog is for hunting, protecting livestock, or protecting crops. While the scholars agree that it is permissible to acquire dogs for the purposes mentioned in the ḥadīths (hunting, guarding livestock, and guarding crops), they disagree concerning other purposes. Ḥanafīs and Mālikīs tend to consider it offensive to obtain dogs for purposes other than the ones mentioned in the ḥadīths. Shāfiʿīs consider it unlawful to obtain dogs that do not fulfill a need similar to the ones mentioned in the ḥadīths (hunting and protecting). Ḥanbalīs consider it unlawful to obtain a dog unless it can carry out one of the tasks in the ḥadīths mentioned above.4
There is also disagreement concerning the use of household guard dogs. In addition to the ḥadīths regarding purity and loss of rewards, there are also ḥadīths mentioning that angels will not enter houses if there is a dog inside. Commentators mention that the angels that are barred are the ones that bring blessings and mercy, and make forgiveness – not the angels assigned to individuals to record their deeds and to protect them. Ḥanafīs tend to say that one should not get a household guard dog unless out of fear for the safety of one’s life or property. Even then, the dog should not be inside the house. There is a fair amount of disagreement amongst the Mālikīs. The well-known opinion I keep finding is that it is offensive to have them inside the house. Shāfiʿīs tend to permit guard dogs for houses and alley ways – and even if the dog is permissible to keep, it should not be kept inside the house.5
What is clear when reading the various opinions within and across the schools is that no one considers it recommended or merely permissible to have a dog in the house. The most lenient ruling is that it is offensive. Some of the scholars who hold this latter position mention that one will still be subject to loss of rewards, and some angels will be barred from the house. So while there is a case for having a dog that serves a valid purpose – there does not seem to be any case for keeping a dog as a pet just for companionship or pleasure – or its appearance.6
Given all the ḥadīths related to dogs (that keeping one without justification reduces rewards, that their presence in a house bars some angels from entering, that there was an order to kill them that was later reduced out of fear of exterminating the entire species, that jet-black dogs are wicked, the extra provisions required to clean up after them – which suggests that they are filthy), one really needs to be very careful before getting a dog. Contrary to some pieces that have been written in English: those reports related to dogs were not related by a single companion (Allah be pleased with them).
Each of the rulings I mentioned above have additional conditions, constraints, and details. All of those things must be known before obtaining a dog.
And Allah knows best.
Dogs today are used for a wide range of tasks not mentioned in our classical books. These tasks include: guide dogs for the blind, security dogs for the police and military, search dogs for humans trapped under rubble, detecting cancer, predicting and warning about seizures, as part of therapy for autism or PTSD, and many others. These tasks are beneficial to muslims. Many of them do not fit cleanly under hunting and guarding. Determining their legal status requires having a clear understanding of the textual evidence and rulings related to dogs, as well as a clear understanding of the contemporary task. And that’s why I have been reading so much about dogs.
The links provided for this and the other ḥadīths enable even a semi-curious English reader to verify that the reports are each narrated from the Prophet (Allah bless him and grant him peace) by three or more companions (Allah be pleased with them all), putting them within the category of well-known (mashhūr or mustafīḍ). All of them are considered rigorously authenticated (ṣaḥīḥ). These reports cannot be waved away with the claim that they are singular (aḥād) or spurious fabrications (mawḍūʿah). If you’re going to dismiss them, at least identify where the chain broke or which one of them lied – you can’t just affirm or deny a specific ḥadīth based on surmise or it being inconvenient. One of the characteristics of Islamic legal scholarship is to use all the evidence that is available, as captured in the maxim that application of an evidence is superior to its abandonment (al-iʿmāl afḍal min al-ihmāl).