Forty men vowed to kill Paul in Acts 23:
14 They went to the chief priests and elders and said, “We have strictly bound [G332-cursed] ourselves by an oath [G331-curse] to taste no food till we have killed Paul.
Gill explained:
it may be asked, what became of this vow? or how did they get clear of it, since they did not accomplish the fact?
These are the questions of interest.
to which it may be answered, that it was a pretty easy thing to be freed from oaths and vows, among the Jews, whose doctors had a power to absolve men from them;
There were learned Jews who were empowered to release them of their vow and they could do so in different ways. No problem.
and in such cases as this, and such a vow as this, might be loosed upon more accounts than one, as on account of keeping another law, the observing the sabbath and other festivals, when men were obliged to eat and drink: and thus it is said (d),
Sorry, I didn't know at the time that my vow would extend into the sabbath. Isaiah 58:13 overrides my vow.
Isaiah 58:
13 If you keep your feet from breaking the Sabbath and from doing as you please on my holy day, if you call the Sabbath a delight and the LORD's holy day honorable, and if you honor it by not going your own way and not doing as you please or speaking idle words,
If the conspirators couldn't wait until the Sabbath, no problem:
and likewise it might be loosed on account of life, which a man is bound to preserve: for so they likewise say
Proverbs 12:18 overrides the vows:
The words of the reckless pierce like swords, but the tongue of the wise brings healing.
and no doubt but these men very easily got their vow loosed, since it was made on such a design.
Now, these extremists were no longer bound by their vows—until the next occasion. Then the cycle repeats. No problem. No wonder Jesus told the Jews in Matthew 5:
34 But I tell you, do not swear an oath at all: either by heaven, for it is God’s throne; 35or by the earth, for it is his footstool; or by Jerusalem, for it is the city of the Great King. 36 And do not swear by your head, for you cannot make even one hair white or black. 37 All you need to say is simply ‘Yes’ or ‘No’; anything beyond this comes from the evil one.
They bound themselves under a great curse, vowing to eat nothing until they had slain Paul. When they failed to slay Paul, they used some legal loophole to get out of the binding.
