Sahih Muslim
The Book Pertaining to Clothes and Decoration (Kitab Al-Libas wal-Zinah)
Book Number: 024 / Hadith Number: 5177
Ali b. Abu Talib reported: Allah's Apostle (may peace be upon him) forbade me to recite the Qur'an while I am in ruku; and the wearing of gold and clothes dyed in saffron.