One of the students studying in the Yeshiva of Slobodka saw a piece of paper on the floor. He bent over to pick it up, thinking that it might have been a scrap from a holy text which would require that it go into a geniza (a burial vault) to maintain its holiness. When he realized, however, that the material written on it was merely some trivial matter, he threw it back on the floor.
The Saba from Slobodka noticed his actions and called him over to speak to him. “It was an act of negligence on your part to toss that paper back on the floor!” he said. “You have now created a hazard in the public domain with that crumpled up paper.” The student was amazed. A “pit” is an obstacle which may cause an animal to stumble into it or a person to get injured. What damage could a simple piece of paper cause?
The Saba noticed the student’s lack of understanding and he explained. “Do not think that a ‘pit’ is only dangerous when you create a trap which may ensnare and injure another person or animal. Even now, you have required another person to have to bend over and to clean up this trash. His path is disturbed and he will be delayed in his studies. You have stolen from his time. This is also a damage, and it falls under the category of “bor” – the prohibition of creating an obstacle which causes harm to others.
“Furthermore, although you are not the one who owns the paper and you did not toss it on the ground originally, you have legally acquired it by lifting it up.” (See Bava Kamma 30a).