And those who lived in the time of the prophets saw the them but they did not see the revelation descending onto them. And we see the revealed books in front of us but we did not see them being revealed. Hence belief in prophethood and in the revealed books are also among the belief in the unseen as well.
Thus, faith is the principle of conviction in what is veiled from the human being and it exists in the heart. And there are other stories in the Holy Qur’an which affirms the principle of resurrection for the people such as the story of the one who passed by a village that had been overturned and said,
﴾مَرَّ عَلَى قَرْيَةٍ وَهِيَ خَاوِيَةٌ عَلَى عُرُوشِهَا قَالَ أَنَّى يُحْيِي هَذِهِ اللَّهُ بَعْدَ مَوْتِهَا فَأَمَاتَهُ اللَّهُ مِائَةَ عَامٍ ثُمَّ بَعَثَهُ﴿
“the one who passed by a township which had fallen into ruin. He said, ‘How is Allah going to bring this back to live after its death?’ Then, Allah caused him to die for 100 years and then raised him up again.”
[Surah Al-Baqarah: 259].
And also in the story of Prophet Isa u who was sent to the children of Israel when he brought the dead back to life by the permission of Allah U. Hence this principle is connected to the resurrection after death. Allah U shows them how He brings the dead back to life so that they will believe in the resurrection.