BT Ara 3a(32) :הא דמסברי ליה וסבר הא דמסברי ליה ולא סבר‏ : this (refers to a case) where they explain (it) to him and he understands, (and) that to where they explain (it) to him and he does not understand
See the entire entry for sbr vb. to expect; to reason