If
an ox was pursuing another ox and the pursued ox was later found
damaged, and the damaged party says: “Your ox caused the damage,” but
the owner of the pursuing ox says, “Not so, rather it injured itself on
a rock” - the burden of proof rests on the one who seeks to exact money
from his fellow.
If two oxen were pursuing an ox and it was
later found damaged, and the owner of one pursuing ox says “Your ox did
the damage,” but the owner of the other says, “No, your ox did the
damage” - both are exempt, because each can shift the blame to the
other.