Overall meaning : We cause whomever We grant long life to revert to weakness after their having been endowed with strength. Will they not, then, understand that the One who can effect such a state is certainly capable of resurrecting them after death?!
We have not taught Muhammad poetry, nor is it fitting for him to be a poet. This Book is but a reminder and a clear Qur’an, so that the Messenger may warn with it those who are alive and can benefit from the warning, and so that the unbelievers become justly deserving of punishment.