Good Manners and Form (Al-Adab)
Bukhari :: Book 8 :: Volume 73 :: Hadith 228
Narrated Anas bin Malik:
Once the Prophet was on one of his journeys, and the driver of the camels started chanting (to let the camels go fast). The Prophet said to him. "(Take care) Drive slowly with the glass vessels, O Anjasha! Waihaka (May Allah be Merciful to you)."