Charles H. Spurgeon on Psalms 118:12

They are quenched as the fire of thorns. The illustration from the "fire of thorns" is derived from the fact that they quickly kindle into a blaze, and then the flame soon dies away. In Eastern countries it was common to burn over their fields in the dry time of the year, and thus to clear them of thorns and briers and weeds. Of course, at such a time they would kindle quickly, and burn rapidly, and would soon be consumed. So the Psalmist says it was with his enemies. He came upon them, numerous as they were, as the fire runs over a field in a dry time, burning everything before it. Albert Barnes.