And David says, “Let their table be made a snare, and a trap, and a stumblingblock, and a recompense to them, let their eyes be darkened, that they may not see, and bow you down their back always.”
The second citation is an adaptation from Psalms 69:22-23 which in LXX reads, ‘Let their table before them be for a snare, and for a recompense, and for a stumblingblock. Let their eyes be darkened that they should not see; and bow down their back continually.' The reference to ‘a trap' is incorporated from MT, but may have been in Paul's LXX text.
The main reason for selecting this verse is the reference to ‘let their eyes be darkened' tying in with the previous citation. But as the idea of them stumbling is taken up in the next verse Paul clearly has the whole citation in mind. The ‘table' would have been a piece of leather unrolled and spread on the floor, which explains how it could become a snare, and a trap and a stumblingblock. The idea behind the whole citation is that what they would normally see as something joyous and beneficial (like a feast piled up on a table) is to become a snare, a trap and a stumblingblock to them. This is precisely what has happened to the unbelieving Jews with the Law. They want to eat of the table that they have set for themselves, with the result that they are not willing to eat at God's table. They want righteousness by the Law. But this has proved to be ‘a snare, and a trap, and a stumblingblock, and a recompense to them'. All it can do is entrap them and make them stumble on in their ignorance.
Some see ‘the table' as referring to the altar in which case there is the idea that they have allowed their ritual to be a snare to them and to cause them to stumble. Compare Isaiah 1:11-18.
We note that in accordance with Rabbinic practise Paul underlines his point from the Law (Deuteronomy), the Prophets (Isaiah), and the Holy Writings (the Psalms), the three division of the Jewish Scriptures.