It is narrated from Sayyiduna Anas (may Allah be pleased with him) that a Bedouin urinated in the mosque. Some people rushed towards him (to scold and stop him), but the Messenger of Allah (peace and blessings be upon him) said: "Do not stop his urination." Then he called for a bucket of water and poured it over (the place).
And the explanation of the evidence that pouring a bucket of water makes the ground pure, even if the place of urine is dug up and thrown outside the mosque, as is the opinion of some Iraqis (that the soil should be thrown outside the mosque), whereas Allah the Exalted has bestowed favor and kindness upon His believing servants by sending His Prophet (peace be upon him) as one who brings ease, not hardship.
Hadith Referenceصحيح ابن خزيمه / جماع أبواب تطهير الثياب بالغسل من الأنجاس / 296