The passage below was written around the turn of the century by A. B. Gottlober, a Jewish author born in Volhynia, Ukraine.  The quote is reproduced by Israel Bartal on p. 313 of his article On Top of a Volcano: Jewish-Ukrainian Co-Existence as Depicted in Modern East European Jewish Literature, which constitutes pp. 309-325 of Howard Aster and Peter J. Potichnyj (editors), Ukrainian-Jewish Relations in Historical Perspective, Canadian Institute of Ukrainian Studies, University of Alberta, Edmonton, 1990.  Israel Bartal, in turn, gives his source as A. B. Gottlober, Ha-gizra ve-ha-binya, in Memoirs and Travels (Hebrew), Jerusalem, 1976, pp. 30-31.

[Bohdan Khmelnytsky] grew stronger and stronger for five successive years, from 5408 to 5412, and he marched through the length and breadth of the land, and everywhere he went, he laid the countryside waste and smote the Poles and Jews mightily, unto destruction.  For the sin of Judea and Israel was inscribed on the tablets of Khmelnytsky's heart with a stylus of steel.  When the leaders of Poland made their yoke heavy upon the necks of the peasants, their serfs, and they oppressed them with hard labour, and they appointed the Jews as their excise officers and the lessors of their fields, to collect taxes from those unfortunate people, and many of the Jews hardened their hearts and showed no mercy to that flock of men, and they became the tools of the cruel noblemen with their high hearts to oppress the peasants and destroy their portion and their flesh.  After Khmelnytsky girded his loins like a hero to free the serfs from their suffering under hard masters, he reached out his arm powerfully against the lords of Poland and turned his attention to the Jews.  It was easy for him to wreak his vengeance upon them and to tread upon them like the dust, as is written in the chronicles of those times, when Jews were held in contempt and Israel was trodden under and ensnared in traps and pitfalls, and they had not spirit to withstand their persecutors.