One of the hallmark Rabbinic interpretive techniques is the identification of parallel wording in two different sections of the Torah. In legal interpretation, this is the foundation for the second of R. Yishmael’s “13 principles by which the Torah is interpreted”: the gezeirah shavah, or “the rule of equivalence.” This principle, first quoted in the name of Hillel the Elder, posits that if the same word or phrase appears in two distinct legal cases in the Torah, that is an indication that we can apply the parameters of one law to the other. The original and paradigmatic form of the gezeirah shavah was one in which the word in question appears only twice in the entire Torah.  When there is only one other location that a linking word takes us to, then the inference from one context to the other becomes especially strong.