Is a small amount of impurity excused?

Question : That is, as long as it is.

Answer : He holds that every small amount of impurity is excused, every small amount of impurity is excused, even the spray from urine. However, the correct view is that urine and whatever the Sunnah specifies for washing are not excused, such as menstrual blood and irregular bleeding. As for blood that comes out from other than the two private parts, there is nothing in the Sunnah indicating that blood coming out of a human being is impure except what comes out from the two private parts. The legal maxim is that what is alive is its carrion, and the carrion of a human being is pure. The jurists themselves (may Allah have mercy on them) mentioned that the blood of fish is pure because its carrion is pure, and so it is with the human being. Also, if his hand were cut off, it would be pure, even though it appears to me that blood is not impure unless it comes out from the two private parts.
As for the claim of consensus on its impurity, there is a need to look into it, for the disagreement on it is established. Yes, if we were to verify that the scholars agreed on its impurity, we would rule it impure. Then, if we rule it impure, we would need evidence for its excuse.
Among the strongest of its evidence for the excuse, and the evidence, as you see, all indicates that the Companions prayed in their blood with their wounds, and that they were afflicted with boils and the like. As for what has changed from blood, such as pus and suppuration, the Shaykh al-Islam holds that it is pure. He says: because this is not blood, it has changed. Likewise, the water of wounds that result from fire burns and the like, it is pure.