Psalms - Chapter 109
I Am Prayer. (Esau? Not So Much.)
David asks that G-d, Whom he always praises, not be silent when enemies are trying to destroy him. Evil people open their mouths to David, trying to trap him with their lies. They have no reason to hate and attack him as they do; they only resent how he constantly tries to get close to G-d. But David prays so much, he essentially IS prayer! They try to repay David's good with evil, and his love of G-d with animosity.
David asks that his enemies become subject to an evil ruler and that accusing angels stand by to prosecute them. He hopes that they be found guilty and their vain prayers be held against them. He hopes that his enemies pass away and are replaced by others in their daily roles. This will leave their wives widowed and their children orphaned, causing others to question what brought this about. The deceased enemies' property will be seized to pay their debts and their unprotected property may be raided. The enemies are so evil that, once they have passed on, no one would want to help their survivors. If the children of these people starve to death, they will be utterly forgotten by the next generation. David asks that the sins of the parents be remembered by G-d, Who should erase any trace of them from the Earth.
Why does David wish such harsh treatment on his enemies? Because they refused to perform acts of kindness, preferring to persecute the needy, hounding them to death. This behavior invited G-d's curse upon them and distanced all blessing. They wore their curse like a cloak and internalized it like water. David hopes that they wear it like a belt instead. (A belt is tight; David is saying that the curse should adhere firmly to the sinners.) When this happens, it will be from G-d to David's enemies, as payment for their evil deeds and slander.
Just as G-d will punish those evil people, David prays that He will favor him. David asks for this not because he thinks he's so wonderful, but because G-d is inherently kind and if David survives, he will serve G-d and praise Him. David feels dead inside, fading like a shadow. He is physically depleted to the point that his detractors mock him for it. David asks for G-d's help so that his enemies will see Him take action. Let G-d bless David, whom they cursed, and let the ones who tried to elevate themselves be humbled. Then David will be the one to rejoice! His enemies will dress themselves in shame when their plots fail, while David will praise G-d publicly; G-d is the One Who saves the weak from their antagonists!
Many parts of this Psalm can be understood as allusions to Esau and his descendants (the Biblical nation of Edom and, later, Rome). For example, verse 17, which says that the enemy in this Psalm did not want the blessing of G-d and distanced himself from it, is taken as a reference to Esau selling Jacob his birthright in Genesis chapter 25. The commentators identify numerous such references throughout this Psalm.