Charles H. Spurgeon on Psalms 141:6

For they are sweet. They shall be pleasant; mild; gentle; equitable; just. After the hash and severe enactments of Saul, after enduring his acts of tyranny, the people will be glad to welcome me, and to live under the laws of a just and equal administration. The passage, therefore, expresses confidence that Saul and his hosts would be overthrown, and that the people of the land would gladly hail the accession to the throne of one who had been anointed to reign over them. —Albert Barnes.

Verses 6-7. The mild and dutiful behaviour of David towards Saul and his friends are set together by way of contrast, in the strongest light, from the instances of each sort here produced. The first is, David's humanity towards Saul, in giving him his life at two several times, when he had it in his power to destroy him as he pleased. "Their judges have been dismissed in the rocky places; and have heard my words that they are sweet"; that is, "Their princes have been dismissed in safety, when I had them at an advantage in those rocky deserts; and only heard me expostulate with them in the gentlest words." The other is, Saul's barbarity and cruelty towards David (or his friends, which is much the same) in the horrid massacre of Ahimelech and the priests, by the hand of Doeg the Edomite, done in such a savage manner, that he compares it to the chopping and cleaving wood; "Like as when one cutteth and cleaveth, so have our bones been scattered on the earth at the command of Saul"; for so I read the Hebrew words, le-pi Saul, at the mouth, that is, the command of Saul. Should we suppose this passage to refer to the first time of David's sparing Saul, viz., when he had him in his power in the cave of Engedi (here called jede selay), the sides of the rock, or the rocky places, the speech he made on this occasion when he called after Saul (and which is recorded in 1Sa 24:8-16.) might well be called sweet or pleasant words. For they set his own innocence and the king's unjust behaviour to him in so strong a light, and with all that gentleness and mildness, and even this hard hearted prince could not forbear being greatly affected with it for the present; and we are told (1Sa 24:16-17) that "he lifted up his voice and wept." —Charles Peters.