Oliver Cromwell

Oliver Cromwell used an expression something like "..by the bowels of christ say it is not so.." does anyone know what the phrase was exactly and in what context he used it?

"I beseech you in the bowels of Christ think it possible you may be mistaken."--
Oliver Cromwell,In a letter to the general assembly of the Church of Scotland. 1650.
The Church of Scotland was pretty much independent till the Reformation. The Reformation was a movement against the Catholic Church.
The result was that the Scottish Parliament officially adopted Protestantism as the country's religion in 1560.
This led to a great deal of protest and unrest especially after the crowns of Scotland and England were united in 1603.
This period of religious unrest was the environment in which your quote was uttered.