Kabbalah sa Mga Awit 51:6: Zohar

It is here fitting to consider why Shimei, who was a scholar and a wise man, behaved to David as he did..The truth is that the words of insult and cursing which he uttered were not his own, but entered into his heart from another region (from heaven), for David’s benefit, that he might repent with a perfect repentance, with a broken heart and with many tears before the Holy One. Therefore David said: “The Lord hath said unto him, Curse David” (Ibid. 5, 10). He knew that the cursing and words of insult were inspired from above.

Was Shimei, then, a fool to accept an oath like this, which forbade David only to kill him with a sword, but not with a spear or arrow?

But this sentence can be taken in two ways. One is based on the saying of the son of the great fish. whose scales reached the highest clouds (i.e. whose wisdom was great), that when David swore he swore by his sword upon which was engraved the Ineffable Name (Tetragrammaton); and thus he swore to Shimei, as it is written: “I sware to him by the Lord (TETRAGRAMMATON)… I will not put thee to death (swearing) by the sword.” But Solomon interpreted it differently. He said: “This man cursed my father with words; he shall die by means of a Word (Tetragrammaton).” And, in fact, he did not kill him with the actual sword, but with the Name. There is still, however, a difficulty, namely, that since David swore to him he ought not to have killed him, and that David said something with his lips which he did not mean in his heart.