And David says, “Let their table become a snare and a trap, a stumbling block and a retribution for them;  let their eyes be darkened so that they cannot see, and bend their backs forever.” (ESV)
The Apostle Paul is quoting Psalm 69:22-23 here in these verses. As you read the Old Testament you need to always dig a little deeper to understand what is being said. David used the word "table" in the verses that Paul is quoting. What is he talking about? David would be talking about a table in terms of a place of safety.
The Israelites were looking to their own works as a place of safety. They were intent on trying to keep the Law as a means of feeling that they were safe and secure in their walk with God. Paul is saying here, by quoting David, that the Israelites table is not the place of safety that they think it is. Rather, depending on their own works for righteousness is a snare and a trap.
Consider that the purpose of the Law was to show all of mankind that we are incapable of keeping it. The Law gives us God's perfect and holy standard. Every time that we look deeply into the Law it shows us just how unholy we are. For the Jews, the very thing that should have brought them to a humble acceptance of their need for a savior was the thing that they stumbled upon in their pride.
While the Jews were struggling to place their faith in the work that God had done for them the Gentiles were placing their faith in God and receiving what the Jews refused to receive. Of course, this does not mean all of the Jews rejected faith in Christ. Many did receive him, the Apostle Paul being one of them. But for others the doctrine of grace turned their table into a snare.
Are you looking to your own efforts to feel secure in your relationship with God. That's a trap! Humble yourself under his mighty and gracious hand. Accept his work on your behalf. Believe in Jesus Christ as your only source of righteousness.