The Prophet ﷺ said, "Between the two blowing of the trumpet there will be forty." The people said, "O Abu Huraira! Forty days?" I refused to reply. They said, "Forty years?" I refused to reply and added: Everything of the human body will decay except the coccyx bone (of the tail) and from that bone Allah will reconstruct the whole body.  

عَنِ النَّبِيِّ ﷺ قَالَ بَيْنَ النَّفْخَتَيْنِ أَرْبَعُونَ قَالُوا يَا أَبَا هُرَيْرَةَ أَرْبَعُونَ يَوْمًا قَالَ أَبَيْتُ قَالَ أَرْبَعُونَ سَنَةً قَالَ أَبَيْتُ قَالَ أَرْبَعُونَ شَهْرًا قَالَ أَبَيْتُ وَيَبْلَى كُلُّ شَىْءٍ مِنَ الإِنْسَانِ إِلاَّ عَجْبَ ذَنَبِهِ فِيهِ يُرَكَّبُ الْخَلْقُ  

Between the two blowings of the trumpet (there would be an interval of forty). They said: Abu Huraira, do you mean forty days? He said: I cannot say anything. They said: Do you mean forty months? He said: I cannot say anything. They said: Do you mean forty years? He said: I cannot say anything. Then Allah would cause the water to, descend from the sky and they (people) will sprout like vegetable. The only thing in a man which would not decay would be one bone (the tailbone) from which the whole frame would be reconstituted on the Day of Resurrection.  

قَالَ رَسُولُ اللَّهِ ﷺ مَا بَيْنَ النَّفْخَتَيْنِ أَرْبَعُونَ قَالُوا يَا أَبَا هُرَيْرَةَ أَرْبَعُونَ يَوْمًا قَالَ أَبَيْتُ قَالُوا أَرْبَعُونَ شَهْرًا قَالَ أَبَيْتُ قَالُوا أَرْبَعُونَ سَنَةً قَالَ أَبَيْتُ ثُمَّ يُنْزِلُ اللَّهُ مِنَ السَّمَاءِ مَاءً فَيَنْبُتُونَ كَمَا يَنْبُتُ الْبَقْلُ قَالَ وَلَيْسَ مِنَ الإِنْسَانِ شَىْءٌ إِلاَّ يَبْلَى إِلاَّ عَظْمًا وَاحِدًا وَهُوَ عَجْبُ الذَّنَبِ وَمِنْهُ يُرَكَّبُ الْخَلْقُ يَوْمَ الْقِيَامَةِ  

Abu Huraira said, "Messenger of Allah ﷺ said, 'Between the two sounds of the trumpet, there will be forty." Somebody asked Abu Huraira, "Forty days?" But he refused to reply. Then he asked, "Forty months?" He refused to reply. Then he asked, "Forty years?" Again, he refused to reply. Abu Huraira added. "Then (after this period) Allah will send water from the sky and then the dead bodies will grow like vegetation grows, There is nothing of the human body that does not decay except one bone; that is the little bone at the end of the coccyx of which the human body will be recreated on the Day of Resurrection." (See Hadith No. 338) (Using translation from Bukhārī 4935)  

قَالَ رَسُولُ اللهِ ﷺ «بَيْنَ النَّفْخَتَيْنِ أَرْبَعُونَ» قَالُوا يَا أَبَا هُرَيْرَةَ أَرْبَعُونَ يَوْمًا؟ قَالَ أَبَيْتُ قَالُوا أَرْبَعُونَ شَهْرًا؟ قَالَ أَبَيْتُ قَالُوا أَرْبَعُونَ سَنَةً؟ قَالَ أَبَيْتُ قَالَ «ثُمَّ يَنْزِلُ اللهُ مِنَ السَّمَاءِ مَاءً فَيَنْبُتُونَ كَمَا يَنْبُتُ الْبَقْلُ» قَالَ «وَلَيْسَ مِنَ الْإِنْسَانِ شَيْءٌ إِلَّا يَبْلَى إِلَّا عَظْمٌ وَاحِدٌ وَهُوَ عَجْبُ الذَّنَبِ» قَالَ وَفِيهِ يُرَكَّبُ الْخَلْقُ يَوْمَ الْقِيَامَةِ  

"مَا بَينَ النَّفْخَتَين أَرْبَعُونَ، ثُمَّ يُنزِلُ اللهُ مِنَ السَّمَاءِ مَاءً فَيَنبُتُونَ كَما يَنْبُتُ الْبَقْلُ، وَلَيسَ مِن الإِنْسَانِ شَيءٌ إِلا يَبْلَى إِلا عَظْمٌ واحِدٌ، وَهَوُ عَجْبُ الذَّنَبِ، وَمِنْهُ يُرَكَّبُ الْخَلْقُ يَومَ الْقِيَامَةِ".