David saw Uzzah drop dead when he touched the ark.
David sacrificed oxen and fattened animals after every six steps toward the city of David.
In other words, David saw how holy God is– one who came so close to his ark that he touched it dropped dead. And David saw the mercy of God on him and on the people of Israel– every ox and every fattened animal that was slaughtered could have been him and anyone else in Israel.
David danced before the holy LORD with all his might when the holy LORD drew near in mercy. Has he not drawn near to us in mercy through the once-for-all sacrifice of Christ (i.e., not every six steps– a much better sacrifice)? Why then are we still seated?