Is it true that had Prophet Adam, peace be upon him, not eaten from the tree, then all of us would have been in Heaven?
All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
There is no doubt that the sin of Aadam (Adam), may Allah exalt his mention, was the reason for him leaving Paradise.
If he had not gone out of Paradise, then the children of Adam would not have been subjected to being commanded to perform obligations and would have remained in the bliss of Paradise.
Abu Hurayrah, may Allah be pleased with him, narrated that the Prophet said, “Aadam and Moosa (Moses) debated with each other, and Moosa said, ‘You are Aadam who turned out his offspring from Paradise…’” [Al-Bukhaari] The narration of Maalik reads, “You are the one who misguided people and turned them out of Paradise...”
Ibn Hajar said, “Misguided means 'you were a reason for the misguidance of those of them who were misguided', and this is a remote reason, because if he had not eaten from the tree, he would not have been driven out of Paradise, and if they had not come out of Paradise, then desires and Satan would not have had a dominant influence on them.”
Finally, we draw your attention to the fact that it is more appropriate for a Muslim to ask about matters that lead to performing good deeds, such as matters related to his faith, his acts of worship, and his dealings (transactions).
Allah knows best.
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