Purity (tahaarah) is not an essential condition for standing in ‘Arafah
Question

What should a pilgrim do if he passes wind when he is going to do tawaaf or is heading towards ‘Arafaat?.
Praise be to Allah.Firstly: 
The majority of scholars are of the view that tawaaf is not valid unless one is in a state of purity. The differences of scholarly opinions have been discussed in the answer to question no. 34695. Therefore, whoever breaks his wudoo’ when he is going to do tawaaf should go and du wudoo’, and then start his tawaaf.  This is undoubtedly preferable and is more on the safe side. 
Secondly: 
As for standing in ‘Arafaat, purity is not a condition, so there is no sin on the pilgrim if he stands in ‘Arafah without wudoo’, and he does not have to do wudoo’ unless he wants to pray. The scholars are unanimously agreed that the standing of menstruating women and those who are junub is valid. 
Al-Nawawi (may Allaah have mercy on him) said in al-Majmoo’ (8/140): Ibn al-Mundhir said: The scholars are unanimously agreed that the standing of one who is not in a state of purity is valid, whether man or woman, such as one who is junub or a woman who is menstruating, etc. End quote.  
But it is mustahabb to stand in ‘Arafah free from both major and minor impurity, because one is going to remember Allaah, and it is mustahabb to have wudoo’ when remembering Allaah. 
See: Kashshaaf al-Qinaa’ (2/494). 
And Allaah knows best.