Reference for Bava Batra 129:7

אמר ליה רב נחמן לרב הונא הלכתא כוותין או הלכתא כוותייכו אמר ליה הלכתא כוותייכו דמקרביתו לבבא דריש גלותא דשכיחי דייני:

In the other case, however, I might think that Rab agrees with Samuel. If again I had only the former statement, I might think that only in that case did Samuel say [that the vendor interprets the terms of sale liberally], but here he agrees with Rab. Hence both statements are necessary.

Jastrow