Final answer:
Marco Polo is the explorer who claimed to have told only half of what he saw on his deathbed and was asked to retract his fables.
Step-by-step explanation:
The explorer who claimed to have told only half of what he saw and was asked to retract his fables on his deathbed in Venice in 1324 was Marco Polo.
Marco Polo, an Italian merchant and explorer, traveled to the far East and the court of Kublai Khan. On his deathbed, he is reported to have said, 'I did not tell half of what I saw.'