Matthew Poole and continuators on 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.

Either 1. by giving them strength to carry their Burden: or rather 2. by encouraging them in their Work with some comfortable Sign of his Presence with them and approbation of their work and manner of carrying the Ark. When they saw that he did not cut off any of the persons employed, as he had done before, but spared and favoured them; which they perceived when they had gone six paces, as appears by 2 Sam. 6. 13.