And so shall you do with his donkey, and so shall you do with his garment, and so shall you do with every lost item of your brother’s that he loses and you find; you shall not be able to hide yourself.
English: “You shall not be able to hide yourself” — but if one has already hidden himself, he is exempt.
On the daf / in context: Once a person has passed by and chosen to ignore the object, the ongoing obligation may no longer apply in the same way (subject to further qualifications).
Type of Learning
Derash limiting the temporal scope of the prohibition.
What Is Learned
The prohibition against hiding oneself is directed at the moment of discovery; after one has already passed by, the legal status may change.