2-samuel 6:7

Smote him there for his error - Uzzah sinned through ignorance and precipitancy; he had not time to reflect, the oxen suddenly stumbled; and, fearing lest the ark should fall, he suddenly stretched out his hand to prevent it. Had he touched the ark with impunity, the populace might have lost their respect for it and its sacred service, the example of Uzzah must have filled them with fear and sacred reverence; and, as to Uzzah, no man can doubt of his eternal safety. He committed a sin unto death, but doubtless the mercy of God was extended to his soul.

For his error - The Hebrew is difficult, and some prefer the reading of the parallel passage, "because ... ask" 1 Chronicles 13:10.

6:7 He died - This may seem very severe, considering his intention was pious, and his transgression not great. But, besides that, men are improper judges of the actions of God; and that God's judgments are always just, though sometimes obscure: it is reasonable, God should make some present examples of his high displeasure against sins, seemingly small; partly, for the demonstration of his own exact and impartial holiness; partly, for the establishment of discipline, and for the greater terror and caution of mankind, who are very prone to have slight thoughts of sin, and to give way to small sins, and thereby to be led on to greater; all which is, or may be prevented by such instances of severity: and consequently there is more of God's mercy, than of his justice, in such actions, because the justice is confined to one particular person, but the benefit of it common to mankind in that, and all future ages.