What does Psalm 38:12 mean?

As a warrior and king, David's enemies were always looking for weaknesses which they could exploit. Psalm 38 describes David's suffering as God rebukes him for sin (Psalm 38:1–4). This part of Scripture does not specify what inspired David's plea. However, it might have been his sin regarding Bathsheba (2 Samuel 12:7–9). In that instance, he abused his kingly authority attempting to cover up adultery. Even in the ancient world, where kings wielded almost unlimited power, such things would threaten the loyalty and love of the people (2 Samuel 15:6). Whatever the cause, David's sin seems to have given his enemies a renewed motivation and intensity in their plotting.

A "snare" was a trap usually placed on a path or hidden in the ground. When an animal stepped on the snare, it would snap shut and entangle the animal. In the context of David's enemies, this would mean their subversive plans to catch him and kill him. Those who wanted to destroy him spent ample time discussing his doom and going over their plans. Likely, David overheard his enemies discussing ways to destroy him, or heard reports from his spies and soldiers about it.

As he hears about enemies plotting to destroy him, David's experience foreshadows what happened to Jesus, his chief descendant. After Jesus healed a man with a withered hand, the Pharisees left the synagogue where the healing took place "and immediately held counsel with the Herodians against him, how to destroy him" (Mark 3:6). Evil never stops scheming to interfere with goodness.