Begg was a Constitutionalist in the old Free Church of Scotland
Sermon on Malachi 3:16, in Scottish Christian Herald, Vol. 1, No. 16, (Edinburgh, 18th June 1836), p. 251, as quoted by David Silversides, The Free Offer: Biblical and Reformed, Buy Marpet Press, 2005, p. 122
If you are resolved, O why should we disturb you before the time? Rejoice and let your heat cheer you; but take heed lest the earth should suddenly real beneath your feet, and in the hour of your extremity you send in despair for those ministers whose warnings you now despise, to administer a consolation which you now put away. Now is the accepted time, God waits to be gracious – his salvation is offered to the chief of sinners – his Spirit can cleanse from all sin – his glory can satisfy the longings of an immortal soul. Flee to the stronghold as prisoners of hope.