The Book Pertaining to the Excellent Qualities of the Holy Prophet (may Peace be upon them) and His Companions (Kitab Al-Fada'il)
Muslim :: Book 30 : Hadith 5746
Anas b. Malik reported that Umm Sulaim was with the wives of Allah's Apostle (may peace be upon him) and a camel-driver had been driving (the camels) oil which they were riding. Thereupon Allah's Apostle (may peace be upon him) said: Anjasha, drive slowly, for you are carrying (on the camels) vessels of glass.