I asked Umm Salama what the Prophet ﷺ used to forbid. She replied, "He used to forbid us from crushing the date pits while cooking, or from mixing raisins and dates together."
حدثنا مسدد حدثنا يحيى عن ثابت بن عمارة حدثتني ريطة
سألت أم سلمة ما كان النبي ﷺ ينهى عنه قالت كان ينهانا أن نعجم النوى طبخا أو نخلط الزبيب والتمر
Takhrij, its isnad is daif. Ahmad narrated it, 6/292, from the hadith of Yahya Qattan, through him. Raytah is unknown, and Kabshah bint Abu Maryam, her status is unknown.