Ablutions (Wudu')
4/68. Chapter:
Urinating in stagnant water
Sahih Bukhari
وَبِإِسْنَادِهِ قَالَ " لاَ يَبُولَنَّ أَحَدُكُمْ فِي الْمَاءِ الدَّائِمِ الَّذِي لاَ يَجْرِي، ثُمَّ يَغْتَسِلُ فِيهِ ".
The same narrator said that the Prophet (ﷺ) had said: "You should not pass urine in stagnant water which is not flowing then (you may need to) wash in it."
Reference : Sahih al-Bukhari 239In-book reference : Book 4, Hadith 105USC-MSA web (English) reference : Vol. 1, Book 4, Hadith 240