In one narration the words are: "Then they will mingle among you."
Ahmad recorded it, and its narrators are the narrators of the Sahih, except Umar bin Abd al-Rahman bin Atiyyah, who is thiqah (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الفتن - أعاذنا الله منها / 12574