Lernaean Hydra
Despite the difficulty, Heracles accomplished these tasks, but Eurystheus in the end did not accept the success the hero had with two of the labours: the cleansing of the Augean stables, because Heracles was going to accept pay for the labour; and the killing of the Lernaean Hydra, as Heracles' nephew, Iolaus, had helped him burn the stumps of the multiplying heads.