What is the wisdom behind prohibiting prayer on the side of the road?

Question:
The side of the road: what is the wisdom in the prohibition?

Answer:
If there is ritual impurity in it, but the hadith is weak. The ruling revolves around its cause; if there is ritual impurity in the garbage dump or the slaughterhouse, that is one thing, but if one prays in a place where there is no ritual impurity, there is nothing wrong with it.
Q: The side of the road?
A: It is better and more cautious to leave off prayer on the side of the road; because the Messenger (peace and blessings be upon him) prohibited sitting on the side of the road and spending the night on the side of the road; because it is exposed to causing harm to people. As for the hadith regarding the side of the road, it is weak, but staying away from it is more cautious.
Q: If he prays, is it valid, meaning?
A: To avoid the disagreement, and the correct view is that the prayer is valid, but leaving it off is better and more cautious; so that he does not expose people –pedestrians– to harm: they might trip over him, or someone might step on him, or someone might collide with him.