Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 170
Narrated Anas bin Malik:
The Prophet came to some of his wives among whom there was Um Sulaim, and said, "May Allah be merciful to you, O Anjasha! Drive the camels slowly, as they are carrying glass vessels!" Abu Qalaba said, "The Prophet said a sentence (i.e. the above metaphor) which, had anyone of you said it, you would have admonished him for it".