Shama-il Tirmidhi
Shama-il Tirmidhi Chapter 026, Hadith Number 002 (177).
Hadith Section/Book: Shama-il Tirmidhi Chapter 26. Rasoolullah Performing Wudu At The Time Of Eating
Ibn 'Abbaas Radiyallahu 'Anhu relates: "Rasulullah Sallallahu 'Alayhi Wasallam once, after relieving himself in the toilet, came out, and was served food. The Sahaabah inquired: 'Will you not perform wudu?'. Rasulullah Saliallahu 'Alayhi Wasallam replied: 'Do I have to perform salaah, that wudu must be performed?'"
Commentary
It has been mentioned in the previous hadith, that it is not mustahab to perform wudu before eating. It is better to be in the state of wudu at all times. Physical cleanliness has an effect on spiritual cleanliness. It is therefore recommended that wudhu be performed after visiting the toilet.