Ahmad ibn Muhammad from Muhammad ibn Sinan from Ibn Muskan, who said: I sent a question to Abu Abdillah عليه السلام, peace be upon him, through Ibrahim ibn Maymun. I said to (ibn Maymun): “Ask Imam عليه السلام about a man who urinates and small drop of his urine touches his thigh, and he prays, then after remembers that he did not wash it.” Imam عليه السلام, peace be upon him, said: "He must wash it and repeat his prayer."