For the source text click/tap here: Bava Kamma 25
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One case of Nezikin that does not appear in the Torah is a case of keren be-reshut hanizak: an ox that enters a private domain and causes damage by goring or similar actions.
While the Tanna Kamma accepts the kal va-homer to the extent that we must conclude that the owner is responsible for damage done by his animal in a private place, but he rejects Rabbi Tarfon’s conclusion, arguing that we cannot hold him more responsible that he was in the primary case. Thus the Tanna Kamma rules that the owner will pay half damage, just like he does in the public domain.
Limiting the conclusions that can be reached by means of a kal va-homer in this manner is called dayyo – “enough.” It is enough to learn a parallel halakha from a kal va-homer, but not more than the original law itself.
The Gemara explains that the concept of kal va-homer – and dayyo – stem from the story of Miriam who spoke inappropriately about her brother Moshe (see Bamidbar 12).
We explore the evolution of the character of Miriam in Bible, Midrash Philo and Dead Sea Scrolls.