Musnad Ahmad 788:228

Waki’ narrated to us, he said: Shu’bah narrated to us, from Abu al-Tayyah al-Dab’i, he said: I heard a man—he described him as being with Ibn Abbas—he said: Abu Musa wrote to Ibn Abbas: "You are a man of your time, and the Messenger of Allah, peace and blessings of Allah be upon him, said: 'The Children of Israel, when one of them was afflicted by something of urine, he would cut it off with scissors.'" And the Messenger of Allah, peace and blessings of Allah be upon him, passed by a *damth*—meaning a soft place—and he urinated in it, and he said: "When one of you urinates, let him seek a place for his urine."