Abu Dawud Book 20, Hadith Number 3697.

Chapter : Drink made from mixing of various kinds of dates or dates and raisins.

Narated By Umm Salamah, Ummul Mu’minin : Kabshah, daughter of Abu Maryam, asked Umm Salamah (Allah be pleased with her): What did the Prophet (PBUH) prohibit? She replied: He forbade us to boil dates so much so that the kernels are spoiled, and to mix raisins and dried dates.