The phrase "he that diggeth a pit shall fall into it" means that those who plot or scheme to harm others will ultimately become the victims of their own malice. This proverb, found in the Bible in Proverbs 26:27 and Ecclesiastes 10:8, suggests that people's evil plans often backfire and hurt them instead. It serves as a warning that attempts to trap or harm others are likely to result in the perpetrator suffering the same fate. 

@birdseye

One way or the other, "he that diggeth a pit shall fall into it", even if it's not in short order!