A beraita teaches: “The very early pious ones would hide and discard their sharp objects by burying them in their fields at a depth of at least three tefachim so that they would not obstruct the plow.”
Our Sages teach here that it is characteristic of righteous and pious people to be extremely careful to take special precautions so that their property would not pose a risk to others or their property. As the gemara states afterwards: Rav Yehuda said, “One who wants to be pious should fulfill (be careful in) matters regarding damages.”
In addition to the example stated in the beraita to bury the potential damagers in the field, the gemara quotes two other methods that our Sages employed to dispose of these items. “Rav Chisda would throw them into a fire. Rava would throw them into the Diglot River (Chidekel River — Rashi).” This halacha of responsibly disposing of sharp objects is codified in Shulchan Aruch Choshen Mishpat 415:3, and the latter two scenarios are mentioned as examples of proper disposal.
I once wondered why the gemara mentions, and Rashi explains, that Rava disposed of his sharp items in the Chidekel River, also known as the Tigris. Why is it important to know which river it was? Also, why did he throw it there and not into a different river? After recalling the commentary of Rashi on Chumash regarding the “Four Rivers” that branched from the river that went out from Eden (Ber. 2:10-14) to water the Garden, I’d like to suggest a possible answer. Rashi describes the names of each of the four rivers, and the nature of each one. While the nature of the other three rivers was to “overflow”, the Chidekel’s nature was “kal” — “flowing lightly and gently”. Therefore it was important for the gemara to note that he disposed of his dangerous items specifically in that river, where they would be safely carried away and not wash up onto land where they could be dangerous.
Bava Kama 30a
