Sahih Bukhari Volume 3, Book 30, Hadith 1994

حَدَّثَنَا إِبْرَاهِيمُ بْنُ مُوسَى، أَخْبَرَنَا هِشَامٌ، عَنِ ابْنِ جُرَيْجٍ، قَالَ أَخْبَرَنِي عَمْرُو بْنُ دِينَارٍ، عَنْ عَطَاءِ بْنِ مِينَا، قَالَ سَمِعْتُهُ يُحَدِّثُ، عَنْ أَبِي هُرَيْرَةَ رضى الله عنه قَالَ يُنْهَى عَنْ صِيَامَيْنِ، وَبَيْعَتَيْنِ الْفِطْرِ، وَالنَّحْرِ،، وَالْمُلاَمَسَةِ، وَالْمُنَابَذَةِ‏.

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.)