Or HaChaim on Exodus 21:26/אור החיים על שמות כ״א:כ״ו

1 וכי יכה איש את עין עבדו, If a man smite the eye of his slave, etc. In Kidushin 24 Rabbi Shimon ben Gamliel and the other rabbis disagree on the meaning of this verse. Rabbi Shimon ben Gamliel holds that the legislation contained in this verse applies only when the master has destroyed the eye of his slave deliberately; the other rabbis hold that even if he had not done so deliberately but had merely aimed his blow at the eye, the slave goes free. According to the rabbis, why did the Torah not begin the verse by writing: "whenever a master destroys the eye of his slave," instead of writing "when he strikes the eye of his slave and he destroys it?" Perhaps the Torah did not use this expression as I would have interpreted it as applying to the eye regardless of the intent which has to accompany such a destruction of the eye.

2The Torah may also have intended to convey that though the eye was not destroyed immediately and totally at the time the master struck the slave but only some time later, the legislation that the slave goes free still applies. This situation is different from the one described earlier when death as a result of an unintentional killing had to occur immediately in order for the killer to be guilty of murder. The opinion of the rabbis is supported by the Torah using the word ושחתה, "he has destroyed it," i.e. even if he had not intended to.