Is it valid to remain silent during the first two cycles (rak'ahs) of the 'Ishā prayer instead of reciting the Fātihah, and why were the Companions forbidden from reciting, as mentioned in the Hadith, and what is this Hadith, and what is obligatory to do?

The hadith narrated by Ahmad and Abu Dawud from Ubadah ibn al-Samit, in which there is a prohibition against the congregant (ma'mum) reciting behind the imam except for the Fatiha, based on the Prophet's (peace be upon him) saying: "Do not do so, except with the Mother of the Qur'an, for there is no prayer for one who does not recite it." The reason for this prohibition is to ensure attentiveness to the imam's recitation. The preponderant and authoritative view (al-rajih wal-mufta bihi) is that reciting the Fatiha is a pillar (rukn) for the congregant in every [prayer] unit (rak'ah), whether in a loud or silent prayer.