Psalms 40:15

Let them be desolate - The word here employed means to be astonished or amazed; then, to be laid waste, or made desolate. As used here, it refers to their purposes, and the wish or prayer is that they might be wholly unsuccessful, or that in respect to success they might be like a waste and desolate field where nothing grows.

For a reward - The word used here - עקב ‛êqeb - means the end, the last of anything; then, the recompence, reward, wages, as being the end, the result, or issue of a certain course of conduct. That is, in this case, the desolation prayed for would be a proper recompence for their purpose, or for what they said. “Of their shame.” Of their shameful act or purpose; their act as deserving of ignominy.

That say unto me, Aha, aha - That use language of reproach and contempt. This is a term of exultation over another; a word of rejoicing at the calamities that come on another; an act of joy over a fallen enemy: Ezekiel 25:3; see Psalms 35:21, note; Psalms 35:25, note. As understood of the Messiah, this would refer to the taunts and reproaches of his enemies; the exultation which they manifested when they had him in their power - when they felt secure that their vexations in regard to him were at an end, or that they would be troubled with him no more. By putting him to death they supposed that they might feel safe from further molestation on his account. For this act, this note of exultation and joy, on the part of the Jewish rulers, and of the people as stimulated by those rulers, the desolation which came upon them (the utter ruin of their temple, their city, and their nation) was an appropriate reward. That desolation did not go beyond their desert, for their treatment of the Messiah - as the ruin of the sinner in the future world will not go beyond his desert for having rejected the same Messiah as his Saviour.