Flavius Josephus, Antiquities of the Jews
William Whiston, A.M., Ed.

[143] A LITTLE before the death of Herod the king, Agrippa lived at Rome, and was generally brought up and conversed with Drusus, the emperor Tiberius's son, and contracted a friendship with Antonia, the wife of Drusus the Great, who had his mother Bernice in great esteem, and was very desirous of advancing her son. Now as Agrippa was by nature magnanimous and generous in the presents he made, while his mother was alive, this inclination of his mind did not appear, that he might be able to avoid her anger for such his extravagance; but when Bernice was dead, and he was left to his own conduct, he spent a great deal extravagantly in his daily way of living, and a great deal in the immoderate presents he made, and those chiefly among Caesar's freed-men, in order to gain their assistance, insomuch that he was, in a little time, reduced to poverty, and could not live at Rome any longer. Tiberius also forbade the friends of his deceased son to come into his sight, because on seeing them he should be put in mind of his son, and his grief would thereby be revived.