12 “Keep me from the trap which they have laid for me”. What was the trap? “If you consent, I spare you.” In the trap was set the bait of the present life; if the bird love this bait, it falls into the trap: but if the bird be able to say, “The day of man have I not desired: You know:” “He shall pluck his feet out of the net,” etc. Two things he has mentioned to be distinguished the one from the other: the trap he said was set by persecutors; the stumbling-blocks came from those who have consented and apostatised: and from both he desires to be guarded. On the one side they threaten and rage, on the other consent and fall: I fear lest the one be such, that I fear him; the other such, that I imitate him. “This I do to you, if you consent not.” “Keep me from the trap,” etc. “Behold, your brother has already consented.” “And from the stumbling-blocks,” etc.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)