The source is the Westminster Chronicle and by the way I didn't pay anything like the current Amazon UK price of £105. Lord, I should want it written out by a monk on parchment for that!
The year is 1388.
'...on 27 April, the Duke of York rose in full parliament on behalf of Sir Simon Burley, who, he declared, had been in all his dealings loyal to the king and the realm; and to anybody who wished to deny or gainsay this, he would himself give the lie and prove the point in personal combat. In reply the Duke of Gloucester said that Burley had been false to his allegiance, and this he offered to prove, if need were, with his own sword arm and without multiplying arguments. At this the Duke of York turned white with anger and told his brother to his face that he was a liar, only to receive a prompt retort in kind from the Duke of Gloucester; and after this exchange they would have hurled themselves upon each other had not the King, with characteristic mildness and goodwill, (my emphasis) been quick to calm them down.
For anyone who doesn't know, Burley was eventually executed, although he doesn't appear to have done anything outstandingly wrong. Except, of course, like various other people, he got up the Duke of Gloucester's nose.
Yet we are all supposed to feel sorry for poor old martyr Gloucester when Richard has him taken out in 1397!