It is possible that they did not travel, so they were urged to travel, to see the fate of those whom Allah destroyed because of their disbelief, and to witness their remnants so that they may take heed. And it could be that they traveled and saw that, but did not take heed, making it as if they had not traveled and had not seen. And it was read: 'So they will have hearts' with the letter 'ya', meaning: they understand what they should understand of monotheism, and they hear what they should hear of revelation. Indeed, it is a pronoun referring to the matter and the story, which can come in masculine and feminine forms. In the reading of Ibn Mas'ud: 'Indeed, it'. And it may be an ambiguous pronoun explained by 'the eyes', and in 'blind' the pronoun refers back to it. The meaning is that their eyes are sound and safe, with no blindness in them. Rather, the blindness is in their hearts. And the blindness of the eyes is not to be considered, as if it is not blindness in comparison to the blindness of the hearts. If you say: What is the benefit in mentioning the chests? I say: What has been established and believed is that true blindness is in the place of sight, which is that the pupil is struck in a way that obscures its light. Its use in the heart is a metaphor and an example. So when it was intended to establish what contradicts the belief of attributing blindness to the hearts as a reality and denying it from the eyes, this imagery needed additional specification and definition, to establish that the place of blindness is the hearts, not the eyes. Just as you say: The sharpness is not for the sword but for your tongue that is between your jaws, your saying 'that is between your jaws' is a confirmation of what you claimed for your tongue and a firm establishment that the place of sharpness is that and nothing else. It is as if you said: I did not deny sharpness from the sword and affirm it for your tongue by accident or oversight, but I intended it deliberately.