Library Eusebius of Caesarea Church History
Book 3
Chapter 12: Vespasian commands the Descendants of David to be sought
He 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.
English translation by Arthur Cushman McGiffert, in Nicene and Post-Nicene Fathers, Series II, Vol. I (eds. Philip Schaff and Henry Wace; Buffalo: Christian Literature Publishing Co., 1890). Public domain. Digital text via New Advent Church Fathers.