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”””"
DaifDaifDaifBook 1 · Hadith 61