Hadith: Between the two blows (of the Trumpet), there will be (an interval of) forty. The people said: O Abu Hurayrah, do you mean forty days? He said: I cannot say anything

عن أبي هريرة رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم : «بين النفختين أربعون» قالوا: يا أبا هريرة أربعون يومًا؟ قال: أَبَيْتُ. قالوا: أربعون سنة؟ قال: أَبَيْتُ. قالوا: أربعون شهرا؟ قال: أَبَيْتُ. «ويَبْلَى كل شيء من الإنسان إلا عَجْبُ الذَّنَب، فيه يُرَكَّبُ الخلق، ثم يُنْزِلُ الله من السماء ماء فَيَنْبُتُونَ كما يَنْبُتُ الْبَقْلُ».
[صحيح] - [متفق عليه]

Abu Hurayrah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: "Between the two Blows (of the Trumpet), there will be (an interval of) forty." The people said: "O Abu Hurayrah, do you mean forty days?" He said: "I cannot say anything." They said: "Do you mean forty years?" He said: "I cannot say anything." They said: "Do you mean forty months?" He said: "I cannot say anything." (The Prophet added) "Everything of the human body will perish except the end of the coccyx (tailbone), and from that part, Allah will reconstruct the whole body. Then Allah will send down water from the sky, and the people will grow like green vegetables."
[Authentic hadith] - [Narrated by Bukhari & Muslim]

Explanation

The great Companion Abu Hurayrah (may Allah be pleased with him) reported that he heard the Prophet (may Allah's peace and blessings be upon him) say that the period between the first blow of the Trumpet, which will cause the people to die, and the second blow, after which they will be resurrected, will be forty. Abu Hurayrah was asked: Forty what: days, months, or years? He refused to reply, as he had not heard a specification for this number from the Messenger of Allah (may Allah's peace and blessings be upon him). Then he mentioned that Allah, the Exalted, will send down rain as thick as men's semen, and from this rain, the people will grow in their graves as seeds grow after a flood. Then the people will be resurrected to their Lord on the Day of Reckoning.