Persian historian Sherafeddin (1399) noting:
”What is the foundation of thy insolence and folly?” he demanded of the Sultan. “Thou hast fought some battles in the woods of Anatolia: contemptible trophies.” Continuing as one champion of Islam to another, he nonetheless conceded: “Thou hast obtained some victories over the Christians of Europe; thy sword was blessed by the apostle of God; and they obedience to the precept of the Koran, in waging war against the infidels, is the sole consideration that prevents us from destroying thy country, the frontier and bulwark of the Moslem world.” In conclusion he urged him: “Be wise in time; reflect; repent; and avert the thunder of our vengeance, which is yet suspended over thy head. Thou are no more than a pismire [an ant]; why wilt thou seek to provoke the elephants? Alas! They will trample thee under their feet.”
Bayezid chose to treat this and a subsequent message with contempt: “Thy armies are innumerable; be they so; but what are the arrows of the flying Tatar against the scimitars and battle-axes of my firm and invincible Janissaries? I will guard the princes who have implored my protection. Seek them in my tents.” He concluded with an insult more intimate in character: “If I fly from thy arms, man my wives be thrice divorced from my bed; but if thou hast not courage to meet me in the field, mayest thou again receive thy wives after they have thrice endured the embraces of a stranger.”
Timur’s message to Bayezid, whatever their content, had been in form diplomatic, following the usage as between equals of inscribing their two names side by side. Now Bayezid deliberately flouted all diplomacy, inscribing his own name in large letters of gold, with Timur’s name below it in small letters of black. To so calculated a double affront, at once domestic and diplomatic, barring the door to negotiation, there could be but a single effective response.
This ended very badly for Bayezid. Timur captured him and subjected him to a series of humiliations, including allegedly making his wife serve him naked and using Bayezid as a footstool. (I’m guessing this is the derivation of “ottoman” to mean footstool, though Kinross does not say so and I’ve never seen any confirmation of it.) Anyway, excessive trash-talking with foreign leaders is a bad idea in general, and was an especially bad idea with Mongol warlords during the 13th and 14th centuries.