1 Samuel 25:21

If it should perhaps happen that we swear carelessly to something which, if carried out, would have most unfortunate consequences, we should know that we should willingly change it [in accord with] more salutary counsel. There is an urgent necessity for us to break our oath, rather than turn to another more serious crime in order to avoid breaking our oath. David swore by the Lord to kill Nabal, a stupid and wicked man, and to destroy all his possessions; but at the first entreaty of the prudent woman Abigail, he quickly took back his threats, put back his sword into its scabbard, and did not feel that he had contracted any guilt by thus breaking his oath in this way.

Indeed, because David swore that he would kill Nabal and then in more considerate forbearance did not, shall we say that we should imitate him by swearing rashly that we are going to do what we see later ought not to be done? But, just as fear confounded the one [Lot] so that he was willing to prostitute his daughters, so did anger confound the other [David] so as to swear rashly. In short, if it were permitted us to make inquiry and ask them both why they did these things, the one could reply, "Fear and trembling are come upon me: and darkness has covered me," and the other also could say, "My eye is troubled through indignation." And so we would not be surprised that the one in the darkness of fear and the other in the indignation of his eye did not see what ought to have been seen so as not to do what ought not to have been done.Indeed, to the righteous David we might with reasonable justice say that he ought not to have become angry, not even with an ingrate who returned evil for good. Even if anger crept upon him, as it does upon a man, at least it ought not to have prevailed so far that he swore to do what he would either do in rage or not do and be forsworn.

And David said: Truly, in vain have I kept, etc. The Lord said, detesting the long foolishness of the proud Jews: Truly in vain for so long a time have I offered the gifts of my grace to those out of their minds compared to other nations, and in return they gave the evil of faithlessness, persecution, and the cross, for the good of the grace I gave. Therefore, I will take the wicked from the land, so that until the morning of the universal judgment, no one from the perverse lineage may be left immune. This was said not so that all faithless Jews before the day of judgment might be shown to be dying, but so that they may be taught to be deserving of death and damnation in all respects. This is similar to when Korah stirred sedition in the desert, the Lord spoke to Moses and Aaron, Separate yourselves from the congregation of this people, so that I may destroy them suddenly (Num. XVI); and yet by their interceding and saying, Almighty God of the spirits of all flesh, will Your wrath rage against everyone because of one sinner? wrath was suspended, and the grace of mercy was bestowed. And on the following day, when the whole multitude murmured against them, he said, Separate yourselves from among this congregation, I will destroy them now. But what He showed that the wicked deserved by just judgment, He changed by mercy through the intercession of the faithful. Therefore, in this place also, under the figure of David, the Lord defers judging what the faithless have deserved, as the following spiritual interpretation of this reading will show. For it follows: