When God helped the Levites - The death of Uzza had deeply impressed both David and the Levites, and it was doubted whether God would allow the ark to be moved anymore. Sacrificial animals were held ready; and when it appeared - by the movement of the ark six paces 2 Samuel 6:13, without any manifestation of the divine displeasure - that God was not opposing but rather helping the Levites in their task, the victims were at once offered.
Related Commentaries of 1 Chronicles 15:26
1 Chronicles 15:26
26 And it came to pass, when God helped the Levites that bare the ark of the covenant of the LORD, that they offered seven bullocks and seven rams.