In Isaiah 28:23-29, a parable is used to describe how the LORD deals differently at various times in history. Just as a farmer must deal with different seeds, soils, and purposes for his crops, so the LORD sometimes deals with His people in one way (tenderness, deliverance) and other times in another way (gives them over to their enemies).
"But his ways are not haphazard; he is working according to a plan. Most of the processes described in the parable suggest pain - ploughing, threshing, grinding - but all contribute to the final good of food production. In a similar way the LORD's sever dealings with his people are directed towards a good end which he constantly has in view..." - Webb, p123.