In Yevamot 37 it is recorded that Rav was in Urta saying one thing, and subsequently changed his opinion while in Tzafra. Is there anything specific about his change of locale which caused his change of option, or was it circumstance?
באורתא אמר רבא הכי ובצפרא הדר ביה In Urta Rava stated this ruling, but in Tzafra he retracted it.