2. The Book of Purification

٢۔ كتاب الطهارة

2.28 The prohibition of urinating into standing water

٢۔٢٨ باب النَّهْىِ عَنِ الْبَوْلِ، فِي الْمَاءِ الرَّاكِدِ

(161) bukhari:239

"You should not pass urine in stagnant water which is not flowing then (you may need to) wash in it."  

(١٦١) البخاري:٢٣٩وَبِإِسْنَادِهِ قَالَ

لاَ يَبُولَنَّ أَحَدُكُمْ فِي الْمَاءِ الدَّائِمِ الَّذِي لاَ يَجْرِي ثُمَّ يَغْتَسِلُ فِيهِ