(11) Business Transactions
كتاب البيوع
(8a) Chapter: Withholding Goods till their Price Rises - Section 1
(8) باب الاحتكار
Mishkat al-Masabih 2892 
Ma'mar reported God's Messenger as saying, “If anyone keeps goods till the price rises he is a sinner.” Muslim transmitted it.
عَن معمر قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنِ احْتَكَرَ فَهُوَ خَاطِئٌ» . رَوَاهُ مُسْلِمٌ
Reference : Mishkat al-Masabih 2892
In-book reference : Book 11, Hadith 129