A small amount of najasah (impurity) affecting purification يسير النجاسة في الطهارة

Praise be to Allah, and may Allah’s peace and blessings be upon the Messenger of Allah, his family and his companions.

As to what follows:

In response to your question, we say, and with Allah Almighty lies all success:

According to Ibn Taymiyyah’s opinion, all small amounts of najasahs (impurities) are pardonable. And Shaykh Ibn `Uthaymin (may Allah have mercy on him) mentioned this view in a number of places and favored it. Moreover, this opinion is acted upon in the past and present. You may say, “Avoiding najasahs (impurities) was more difficult and complicated in the past, contrary to the present.” However, the issue of avoiding and being able to avoid differs according to the different states of people, like a sick person whose sickness prevents him from complete movement (moving freely), so his state of being is not as that of a healthy person.  The point is that the ruling that Shaykh al-Islam (may Allah have mercy on him) mentioned, and which was attributed to him by Shaykh Ibn `Uthaymin and also favored by him (may Allah have mercy on him), was acted upon in the past and present. However, this issue, from the perspective of its origin, is one of scholarly dispute, as the majority of scholars are of the opinion that neither a small amount nor a large amount of najasah (impurity) is pardonable, except for what an exception has been made in certain instances in a limited number of cases mentioned by the scholars. As for everything other than that, then it is not pardonable.

However, the correct opinion is that which was mentioned by Shaykh Ibn `Uthaymin (may Allah have mercy on him), and which was chosen by Shaykh al-Islam Ibn Taymiyyah (may Allah have mercy on him), that a small amount of najasah (impurity) is pardonable.

As for the measurement of a small amount of najasah (impurity), then it is what is little, and the reference for that goes back to the custom of the people. As such, there is no specific limit to say “this is a small amount” and “this is a large amount”, rather the reference for this is what is acted upon by the people and their custom, as this is the defining factor for whatever has not been explicitly defined in the Shari`ah. It is as the poet, and he is our Shaykh, said in his poem:

And everything that has come without being defined,

In the Shari`ah, such as a safety place (for safeguarding items from theft), then by custom define it.

So the reference for this (i.e. small amount) goes back to the definition of the custom. Thus, whatever the people consider as being a small amount is what is pardonable, and whatever is not considered as being a small amount is not pardonable. However, as a general rule, as long as it is within the ability of a person to avoid the najasah (impurity), then there is no doubt that it is safer to avoid both the small and large amount of it, so long as it does not lead to phobia.