The Messenger of Allah said: "Do not soak Az-Zahuw and ripe dates together, nor Al-Busr and raisins together. Soak each one of them on its own."
Sunan an-Nasa'i Book 51, Hadith 28
← Previous Hadith Anas would not leave any dates that had become ripe but he would remove them from his Fadikh.

Sunan an-Nasa'i Book 51, Hadith 27 Next Hadith → The Prophet forbade mixing Az-Zahuw and dried dates, and mixing Al-Busr and dried dates, and he said: "Soak each one of them on its own in vessels that are tied shut."

Sunan an-Nasa'i Book 51, Hadith 29