حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا أَبُو أُسَامَةَ، عَنْ عَبْدِ اللَّهِ بْنِ يَحْيَى التَّوْأَمِ، عَنِ ابْنِ أَبِي مُلَيْكَةَ، عَنْ أُمِّهِ، عَنْ عَائِشَةَ، قَالَتِ انْطَلَقَ النَّبِيُّ ـ صلى الله عليه وسلم ـ يَبُولُ فَاتَّبَعَهُ عُمَرُ بِمَاءٍ فَقَالَ " مَا هَذَا يَا عُمَرُ " . قَالَ مَاءٌ . قَالَ " مَا أُمِرْتُ كُلَّمَا بُلْتُ أَنْ أَتَوَضَّأَ وَلَوْ فَعَلْتُ لَكَانَتْ سُنَّةً " .
It was narrated that 'Aishah said: "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.'" Translation Not Available
Book Ref: Sunan Ibn Majah Book 1 Hadith 327
Web Ref: Sunan Ibn Majah Vol 1 Book 1 Hadith 327