פּירוש אויף תהילים 73:9

They set The emphasis, in place of the implication that they spoke about me and my late father with contempt, is explained as the doubling of the root "שתת" (to set or place), meaning their mouths were set in motion as if speaking in the heavens, indicating that they speak about God without knowledge of Him.

And their tongue walks in the land. In other words, their actions and words, which are carried out on Earth, are observed by Heaven.