"The Prophet went out to urinate, and 'Umar followed him with water. He said: 'What is this, O 'Umar?' He said: 'Water.' He said: 'I have not been commanded to perform ablution every time I urinate. If I did that it would have become a Sunnah.'"  

قَالَتِ انْطَلَقَ النَّبِيُّ ﷺ يَبُولُ فَاتَّبَعَهُ عُمَرُ بِمَاءٍ فَقَالَ مَا هَذَا يَا عُمَرُ قَالَ مَاءٌ قَالَ مَا أُمِرْتُ كُلَّمَا بُلْتُ أَنْ أَتَوَضَّأَ وَلَوْ فَعَلْتُ لَكَانَتْ سُنَّةً