The Ruling on the Urine of a Child

The third question in the letter of our brother Muhammad Bakri states: Sometimes the clothes of my young son are wet with impurity, and he touches, without realizing it, the clothes of his older brother or my clothes. However, the marks of the wetness do not appear on the older brother's clothes as a result of the contact. Is it obligatory for the older brother to wash his clothes to purify them, or are they not considered impure because the marks of the wetness did not appear on them? Is there a method of purification from impurity other than washing, such as exposure to the sun? And is there an age at which a boy's urine is not impure, or is it impure from birth? Please inform us, may Allah reward you.
Answer: The urine of a child is absolutely impure from the time of birth until the end of his life. It is impure, but in the state of infancy and before eating food, its impurity is lightened. Sprinkling and dashing water are sufficient for it until he eats food and is nourished by food. Once he is nourished by food, it must be washed, based on the saying of the Prophet (peace and blessings be upon him): .
The point is that as long as he is not nourished by food, his urine is a light impurity for which sprinkling and dashing water are obligatory. If the child's garment is wet with impurity and then touches another pure garment, this wetness makes the garment it touches impure, provided it is wet. If it is wet, it affects the garment it touches. However, if its wetness is light and does not affect the garment it touches, there is no harm; it does not become impure. But if its wetness is clear and distinct, it must affect the garment it touches, even if that effect is not visibly apparent. One should wash the part of the new, pure garment that was affected by this wetness, seeking it out and washing it with water. There is no way other than water. The sun is not sufficient; it must be washed with water. For this reason, when the urine of a child would fall on the Prophet (peace and blessings be upon him), he would pour water on it. If the child was young, he would follow it up with water, but he would not wring it out or wash it thoroughly; sprinkling it with water was sufficient, as mentioned earlier.