Is it permissible to delay the 'Isha and Tarawih prayers in Ramadan for an hour or two?

The jurists have agreed that the preferred time for the 'Isha prayer begins with the disappearance of the red twilight. They differed concerning its end. Some said it extends until the first third of the night, some until the middle of the night, and some until just before Fajr, based on the hadith of 'Aisha: "One night, the Prophet (peace be upon him) delayed the 'Isha prayer until most of the night had passed, then he came out and prayed, and said: 'This is its [preferred] time, were it not that I would cause hardship for my nation.'" The Imam should consider the circumstances of his congregation regarding advancing or delaying the prayer, based on the hadith of Jabir: "The Messenger of Allah (peace be upon him) used to pray Dhuhr in the scorching heat, 'Asr while the sun was clear, Maghrib when the sun had set, and 'Isha sometimes he would delay it and sometimes he would hasten it. If he saw them gathered, he would hasten; and if he saw them delaying, he would delay." There is no harm in delaying 'Isha and Taraweeh prayers if it does not cause hardship for the congregation.