What is the textual and authorial evidence for the purity of the Prophet's urine and blood, and what are the criteria for identifying the particularity of Prophetic hadiths?

Urinating in the mosque is an impurity that must be removed by pouring water over it. Scholars have unanimously agreed on the impurity of human urine, except for the urine of the Prophet, peace and blessings be upon him, which is an exception according to those who deem it pure. Similarly, human blood is impure according to the majority of scholars, though a group has held it to be pure. Those who held blood to be impure excepted the blood of the Prophet, peace and blessings be upon him, considering it pure. As for those who held human blood to be pure, the blood of the Prophet, peace and blessings be upon him, is pure to them like any other blood.