The Shaykh (Al-Mufid), may Allah سبحانه وتعالى support him, said: "And every one of the five obligatory prayers has two times: an initial time and a final time. The first is for one who has no excuse, and the second is for those with excuses. And it is not appropriate for anyone to delay the prayer beyond its initial time while being mindful of it and not prevented from performing it. If he delays it and then dies during the time before performing it, he has neglected it. But if he remains until he performs it at the end of the time or between the first and the last time, he is excused for the delay." We have already clarified previously that the end of the time is for one who has an excuse or a pressing need, and that one who has no excuse, his time is the beginning of the time. What further confirms this is what was narrated:
Commentary #19