Mukhtasar Bukhari

Narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: "The interval between the two trumpet blasts is forty." The people asked Sayyiduna Abu Hurairah, "Forty days?" He said, "I cannot say." (The questioner) said, "Forty years?" He said, "I cannot say." (The questioner) said, "Forty months?" He said, "I cannot say." (And he said that in the grave): "The whole body of a human being decays except the coccyx, and from this (coccyx) the whole body will be reassembled (again)."