Jaabir Radiyallahu 'Anhu says:
"Rasulullah Sallallahu 'Alayhi Wasallam came to visit me (while I was ill). He did not come on the back of a mule, or on a Turkish horse". (i.e. He did not come on defective or an expensive conveyance, but came on foot).
English reference: Book 46, Hadith 321
Arabic reference: Book 47, Hadith 338