They drive away the ass of the fatherless. This was another form of oppression. "Whose ox have I taken? or whose ass have I taken? or whom have I defrauded? whom have I oppressed?" says Samuel, on laying down his judgeship (1 Samuel 12:3).
The "fatherless" were particularly liable to such ill treatment, seeing that they had lost their natural protector. They take the widow's ox for a pledge. It may be true that this was nowhere a legal offence, not even among the Hebrews (Lee); but it was a real act of oppression, and forms a fitting counterpart to the injury done to the orphan.
(On the natural tendency of selfish men to bear hard on these two classes, see Exodus 22:22; Deuteronomy 24:17; Deuteronomy 27:19; Psalms 94:6; Isaiah 1:23; Isaiah 10:2; Jeremiah 5:28; Zechariah 7:10.