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