And David said to Abishai, Destroy him not: for who can stretch forth his hand against the LORD'S anointed, and be guiltless?
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George Leo Haydock
Guiltless. Saul was still his king, how wicked soever, and this title rendered his person inviolable. The eastern nations are very seldom guilty of rebellion, or of murdering their kings; a thing of which we find so many examples in the Roman, English, and French histories. (Calmet)
A private man could not lay violent hands upon the king without a crime; and therefore David represses Abisai, and commits his cause to God, chap. xxiv. 13. (Menochius)
He will not permit any one to destroy the life of the king, though he was already anointed to succeed him. (Worthington)