Is it permissible for the Imam to extend the time between the Adhan and Iqamah to a full hour for the Fajr and Isha prayers, and is one who prays individually immediately after the Adhan and forsakes the Imam's congregation, which is held later, considered sinful?

The Sunnah did not specify a particular time between the Athan and the Iqamah, and the matter is left to what the people of each mosque commonly agree upon, while ensuring sufficient time for people to prepare for the prayer.

The following must be observed: 1. Determining the time of the Iqamah is the right of the Imam, and he should consider the best interest of the mosque's congregants. 2. The Maghrib prayer should be hastened in all circumstances, and its Iqamah should not be delayed except for the time it takes to perform ablution and pray two rak'ahs. 3. It is recommended to delay the Iqamah of the ‘Isha prayer if it does not cause hardship to the people. 4. If people in some countries have commonly agreed upon specific times or if an official directive has been issued, the Imam must adhere to it to avoid disruption and missing the congregation. 5. If the Imam deems it beneficial to delay the Iqamah, but the congregants find it difficult, he should be advised. If he does not comply, it is not permissible to defy him or establish the prayer without his permission, as this would cause disunity among Muslims. In such a case, one may pray in another mosque or wait for the Imam.