The 202nd mitzvah is that we are commanded to unload the burden of an animal which has buckled under its load in a field.

The source of this commandment is G‑d's statement1 (exalted be He), "If you see the donkey of someone you hate lying under its load, ... you must make every effort to help him."

In the words of the Mechilta: "The phrase 'you must make every effort to help him' refers to unloading." There it also says, "From the phrase 'you must make every effort to help him' we learn that the violator transgresses a positive command and a prohibition." This means as follows: we are commanded to take the load off her, and are forbidden from leaving her lying under her load, as will be explained in the Negative Commandments.2 And if he left her lying under her load he transgresses both a positive and negative commandment. This proves that the phrase "you must make every effort to help him" constitutes a positive commandment.

The details of this mitzvah are explained in the second chapter of tractate Bava Metzia.3