Ibn 'Umar Radiyallahu 'Anhu reports:
"Rasulullah Sallallahu 'Alayhi Wasallam called a hajjaam, who treated Rasulullah Sallallahu 'Alayhi Wasallam. Rasulullah Sallallahu 'Alayhi Wasallam inquired from him what tax or duty did he have to pay daily? He replied, three saa'. Rasulullah Sallallahu 'Alayhi Wasallam had it reduced to two saa', and gave him his remuneration".
English reference: Book 49, Hadith 346
Arabic reference: Book 50, Hadith 363