Nicene and Post-Nicene Fathers: Series II/Volume I/Church History of Eusebius/Book III/Chapter 12

Vespasian commands the Descendants of David to be sought.

also relates that Vespasian after the conquest of Jerusalem gave orders that all that belonged to the lineage of David should be sought out, in order that none of the royal race might be left among the Jews; and in consequence of this a most terrible persecution again hung over the Jews.