Parashas Bechukosai · Aliyah 1 · Passuk 3 · Unit 2
Chabad.org — English translation + Rashi
Torah Temimah cites Kiddushin 61b (R’ Meir: every condition that is not like the condition of the children of Gad and Reuven is not a valid condition).
E-Daf / source link
HebrewBooks / classical text
English: It was taught: Rabbi Meir says, any condition that is not like the condition of the children of Gad and the children of Reuven is not a (valid) condition — and that is why Scripture writes both “If you walk in My statutes” and “If you reject My statutes.”
Halachic derasha / formal condition — double condition (tenai kaful) modeled on Bnei Gad and Bnei Reuven.
The blessing and curse sections form a double condition: the positive and the negative must both be stated. Without the explicit opposite, the condition would be incomplete according to R’ Meir’s rule.