Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with him) said: The Noble Prophet (peace and blessings be upon him) was asked about the Sur (Trumpet), so he (peace and blessings be upon him) said: "It is a horn in which it will be blown."
(Commentary on Hadith 2832) On the Day of Resurrection, the trumpet (sur) will be blown, by which all living beings will die, and then the trumpet will be blown again, by which all people—from the beginning of creation until the Day of Resurrection, all who have died—will be brought back to life, and in the gathering (hashr), everyone will be held accountable before Allah Ta‘ala. This is also mentioned in the Noble Qur’an: «﴿وَنُفِخَفِيالصُّورِفَصَعِقَمَنْفِيالسَّمَاوَاتِوَمَنْفِيالْأَرْضِإِلَّامَنْشَاءَاللّٰهُثُمَّنُفِخَفِيهِأُخْرَىفَإِذَاهُمْقِيَامٌيَنْظُرُونَ﴾ [الزمر : 68]» Translation: “And the trumpet will be blown, so all who are in the heavens and all who are on the earth will fall down unconscious, except whom Allah wills. Then it will be blown again, and at once they will be standing, looking on.”