Bava Metzia 32 - Unloading and Loading

If one saw another person's animal lying under its burden, and he unloaded it, allowing it to get up, and then reloaded the burden upon it, and then shortly thereafter, the animal lay down again, he is still obligated to unload or reload as necessary, for it is stated: "... help, you shall help ..."
If the owner impudently walked away and sat down, saying to the bystander, - "Since the commandment to unload my animal is incumbent upon you, if you wish to unload, then unload, but I shall not help you" - the bystander is exempt, for it is stated "... you shall help with him ..."