or Sir Isumbras. A hero of mediæval romance, first proud and presumptuous, when he was visited by all sorts of punishments; afterwards penitent and humble, when his afflictions were turned into blessings. It was in this latter stage that he one day carried on his horse two children of a poor woodman across a ford. (See Ysambras.)
I warne you first at the begynninge That I will make no vain carpinge [talk] Of deeds of armys ne of amours, As dus mynstrellës and jestours, That makys carpinge in many a place Of Octoriane and Isembrase.
William of Nassington.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894