Which verse indicates that a person is punished for the intention to commit a sin in the Sacred Mosque, and why is the sin considered two sins? And did the Quran refer to a person's pulse quickening at high altitudes, leading to fatigue and distress?

Intending to commit a forbidden act falls into categories: if one intends to commit it, then refrains out of fear of Allah, they are rewarded for it. If one intends to commit it, then refrains out of fear of created beings, they are sinful for it. As for a passing, disliked thought, it is forgiven. As for firm intentions: if it pertains to actions of the heart, such as envy, one is held accountable for it. If it does not pertain to actions of the heart, such as drinking wine, there are different opinions: accountability for it, or no accountability, or accountability for it only within the Sacred Precinct (Haram).

The third opinion, which is the subject of the question, states: one is not held accountable for merely intending to commit a sin unless that intention is to commit it within the Sacred Precinct, due to Allah’s saying: (And whoever intends therein [i.e., in Makkah] to deviate [from the right] with injustice – We will make him taste of a painful punishment). In this case, sins committed within the Sacred Precinct are multiplied in terms of quality, not quantity; meaning, they are grave sins whose recompense is equally grave. However, if the intention is coupled with the action, then one is punished only for the action, not for the intention itself.