Ahmad ibn Muhammad narrated from Ali ibn Al-Hakam, from Abu Ishaq Al-Nahwi, from Abu Abdullah عليه السلام. He said:
I asked Imam عليه السلام about urine that touches the body. Imam عليه السلام said: "Pour water over it twice."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 1, p. 265