The Messenger of Allah ﷺ said, "Between the two blasts of the Trumpet there are forty."The people asked, "Abu Hurayrah, forty days?"He replied, "I refuse to say."They asked, "Forty months?"He replied, "I refuse to say."They asked, "Forty years?"He replied, "I refuse to say.""Then Allah will send down water from the sky, and they will sprout just as vegetation sprouts. Every part of a human being decays except for one bone, the tailbone, and from it creation will be reassembled on the Day of Resurrection."
قال رسول الله ﷺ: ما بين النفختين أربعون قالوا: يا أبا هريرة أربعون يوما؟ قال: أبيت، قالوا أربعون شهرا؟ قال: أبيت، قالوا: أربعون سنة؟ قال: أبيت، ثم ينزل الله من السماء ماء فينيتون، كما ينبت البقل قال: وليس من الإنسان شيء إلا يبلى، إلا عظما واحدا، وهو عجب الذنب، ومنه يركب الخلق يوم القيامة.
Bukhari narrated it in tafsir (4935) and Muslim in fitan and the signs of the Hour (2955), both of them through Abu Muawiya, from Amash, from Abu Salih, from Abu Hurairah, who said, and then mentioned it. The wording is that of Muslim, and the wording of Bukhari is similar.