Sahih Bukhari | Volume 3 | Hadith Number 213

Narrated by Abu Huraira
Two fasts and two kinds of sale are forbidden: fasting on the day of 'Id-ul-Fitr and 'Id-ul- Adha and the kinds of sale called Mulamasa and Munabadha. (These two kinds of sale used to be practiced in the days of Pre-Islamic period of ignorance; Mulamasa means when you touch something displayed for sale you have to buy it; Munabadha means when the seller throws something to you, you have to buy it.)