What is the ruling on doing wudoo’ in the mosque?

Praise be to
Allaah.

There is nothing wrong with that. The imaams
of the salaf and the scholars allowed that. Ibn al-Mundhir narrated
in al-Awsat that there was consensus on this matter. He said,
“There is no apparent sense in not allowing that, because the water
is pure and the body of the man is pure, so the water coming out of
his body is also pure, therefore it does not contaminate the place.
But I regard it as makrooh to do wudoo’ in the place where people pray
lest the splashing of the water disturb the people. 

It was narrated that Ibn ‘Abbaas said that
there is nothing wrong with that. This was narrated by Ibn al-Mundhir
in al-Awsat

Ibn Abi Shaybah and Ibn al-Mundhir narrated that
Ibn ‘Umar (may Allaah be pleased with them both) used to do wudoo’ in
the mosque. 

The issue of wudoo’ does not include the issue
of relieving oneself. Relieving oneself in the place where people pray,
whether by urinating or defecating, is haraam by scholarly consensus.