出典:Wiktionary
According to Garner's fourth edition, it's an elliptical nominative absolute standing for that having been said.
言うことには
that
言っていた
わけを言う
. . .even if you said such a thing
You said such a thing, but. . .
supposing that
とのことでしたが
言うまじと
うそを言う
うそを言う
to speak of something
an excuse for something
明らかなさま
どのもの
which
例のあれ