Commentary for II Samuel 6:3

On a new wagon. [Dovid] made a mistake about something that even children at their Rebbe's school know "Because the sacred work was [incumbent] upon them, which they had to carry on their shoulders" (Bamidbar 7:9). And because [Dovid] said, "Your statutes were songs for me in the house of my dwelling,"¹Hashem said to Dovid, “The words of the Torah upon which it is written, ‘Blink your eyes [and be distracted] from it and it is gone’ (Mishlei 23:5), you are calling songs?” (Sotah 35a). A song is of only temporary interest and then forgotten (Maharsho, ibid). (Tehilim 119:54) he was punished to come to this,²Making the mistake of transporting the Ark by wagon. and [to have] Uzoh die through his hand. Therefore³After learning from this mistake. when they brought [the Ark] from the house of Oveid they brought it by shoulder as it says (Divrei Hayomim I, 15:12), "And he said to them, 'You, the heads of households for the Levites, you and your brothers sanctify yourselves and bring up the Ark… because, the first time you did it not.⁴Transporting the Ark on your shoulders. Hashem, Elokeinu made a breach upon us because we did not consult with Him as was proper'."⁵Consequently leading to our tragic mistake.