From a scholion on Aristophanes, Frogs 175 (web address 1), where Dover prints e)a\n cumbw= ti/ soi and translates 'to see if...', 'in the hope that...'. He rejects the reading i(/na (in the Ravenna and Venetus mss) as 'less idiomatic', but the scholion quotes Homer, Iliad 7.353 (web address 2), to justify it.
On this Homeric verse, Walter Leaf comments: "evidently added in order to supply a verb to the phrase ou)/ nu/ ti ke/rdion h(mi=n, which does not need one. The clause i(/na mh\ r(e/comen w(=de cannot be translated so as to make good sense; it looks as though it were meant for 'unless we do thus', perhaps where (= in the case where) we do not thus. But for such a sense the Greek language affords no support. Aristarchus, while obelizing the line, read i(/n' a)\n for i(/na, which does not help matters; e)ktele/esq' ei)/ ken is the only satisfactory variant."