`Ilbaa bin Ahmar Al-yashkari says that the Sahaabi, Abu Zayd `Amr bin Akhtab Al-Ansaari Radhiallahu Anhu said to me:
"Rasullullah (Sallallahu alaihi wasallam) once asked me to massage his waist. When I began massaging the back, accidentally (by chance) my fingers touched the Seal of Prophethood. `Ilbaa (Radhiallahu anhu) says: `I asked Amr (Radhiallahu anhu), what is the Seal of Prophethood?' He replied: `It was a collection of few hair'".
English reference: Book 2, Hadith 19
Arabic reference: Book 2, Hadith 20