Albert Barnes Commentary 1 Samuel 6:14

"And the cart came into the field of Joshua the Beth-shemite, and stood there, where there was a great stone: and they clave the wood of the cart, and offered up the kine for a burnt-offering unto Jehovah." — 1 Samuel 6:14 (ASV)

A great stone - (Judges 13:19). This great stone was probably used as an altar on this occasion, and the cows stopping at it of their own accord was understood by the Bethshemites as an intimation that they were to offer sacrifices on it to the LORD God of Israel, who had so wonderfully brought back the ark from its captivity.

And they split the wood of the cart... - A similar expedient was resorted to by Araunah (2 Samuel 24:22) and by Elisha (1 Kings 19:21).