John Calvin Commentary Psalms 41:7

"All that hate me whisper together against me; Against me do they devise my hurt." — Psalms 41:7 (ASV)

All they that hate me whisper together against me. Here he seems generally to include both classes of his enemies: those who sought to oppress him openly, as avowed enemies, and those who, under the pretense of friendship, attempted to do the same thing by deceit and stratagem. Accordingly, he says that all of them consulted together about his destruction.

This is just as we know that wicked men hold many secret consultations concerning their intended treacherous deeds, whispering to one another about them. Therefore, he adds the words to meditate, or plot, which he uses to indicate their base conspiracies and sinful consultations.