Kaa'b bin Maalik Radiyallahu 'Anhu says:
"Rasulullah Sallallahu 'Alayhi Wasallam licked his fingers thrice (after eating)". (JA)
English reference (JA): Book 23, Hadith 130 (JA)
Arabic reference (JA): Book 24, Hadith 137 (JA)