7. Send thy hand, etc. In one word we are now made to see what was meant by the figures formerly used — that in the absence of all earthly help, God would put forth his hand from above, the greatness of the exigency making extraordinary help necessary. Accordingly he compares his enemies to great and deep waters. He calls them strangers, not in respect of generic origin, but character and disposition. It were a mistake to refer the term to the uncircumcision, for David rather animadverts upon degenerate Jews who gloried in the flesh; and shortly afterwards he hints that he had to do with internal foes rather than a foreign enemy, who would openly assault him with violence and arms. By the right hand of falsehood some understand rash attempts, which David hoped would be frustrated. Others limit the phrase to the solemn ceremony of taking an oath, as if he said they were perjured; (263) while others explain it as meaning that they not only lied with the tongue, but executed wicked devices with the hand. (264) But as it was customary in making promises to join hands, as Solomon says, (Proverbs 11:21; Proverbs 16:5,) I have no doubt David’s reference here is to false, treacherous, and perfidious persons. The two things go naturally together in the verse — the lying tongue and the deceitful hand, meaning upon the matter that nothing was to be looked for from any of their promises, since it was only to deceive that they flattered with their mouth and gave the hand.
(263) “In taking an oath the right hand was lifted up. The enemies of David profaned their oaths by violating the covenants into which they entered, and breaking their solemn engagements.” — Walford.
(264) “The meaning is, the hands with which they confirm their treaties of peace and leagues of friendship are immediately lifted up against the lives and liberties of their allies.” — Warner.