The true opinion states that the Tarawih Prayer is not valid before the `Isha‘ Prayer. There is no disagreement among the jurists that the Tarawih Prayer is valid after the `Isha‘ Prayer; however, it is better that Muslims pray the sunnah Prayer of `Isha‘ before the Tarawih Prayer. Muslims should not neglect the sunnah Prayer after `Isha‘, as it is sunnahmu`akkadah (confirmed Sunnah) and the Tarawih Prayer does not substitute for it.

If the people of a certain mosque are not used to giving time for the people to pray these two rak`ahs, they should be kindly advised to follow the Sunnah. If they refuse, there is no need for dissension. The sunnah Prayer can be performed after the Tarawih Prayer, or one can perform the first two rak`ahs of the Tarawih Prayer with the intention to perform the sunnah Prayer of `Isha‘, and then complete the Tarawih Prayer.

Muslims should observe the two rak`ahs of sunnah after `Isha‘, as Umm Habibah (may Allah be pleased with her), the wife of the Prophet (peace and blessing be upon him), narrated that she heard him say, “If any Muslim servant (of Allah) prays for the sake of Allah twelve rak`ahs (sunnah prayers) every day, over and above the obligatory ones, Allah will build for him a house in Paradise, or a house will be built for him in Paradise” (Al-Bukhari and Muslim). Umm Habibah (may Allah be pleased with her) said, “I have not abandoned observing them after (hearing it from the Messenger of Allah).”

It is stated in the Kuwaiti Encyclopedia of Fiqh that the majority of the jurists assert that the Tarawih Prayer is sunnahmu`akkadah and it should be performed after the `Isha‘ Prayer. The Tarawih Prayer is considered a sunnah Prayer, as it is performed after the obligatory Prayer. Its time starts after performing the sunnah Prayer of `Isha‘ and ends shortly before Fajr, to leave time to pray the Witr Prayer. It is preferable not to delay it, if one will miss the prayer in congregation.

Moreover, the Kuwaiti Encyclopedia mentioned the madhhabs of the scholars as follows:

The majority of the scholars hold the opinion that the time of the Tarawih Prayer is after the `Isha‘ Prayer until the Fajr [Prayer], before performing the Witr Prayer, as the Prophet’s Companions (may Allah be pleased with them) used to pray it during this time. If a Muslim prays it after the Maghrib Prayer and before the `Isha‘ Prayer, the majority of jurists and many Hanafis hold the opinion that it does not replace the Tarawih Prayer and the Malikis say that it is a nafl (supererogatory) Prayer. However, some Hanafis say that it is valid, as all the night—before and after `Isha‘—until Fajr is a time for the Tarawih Prayer. The Hanbalis say that it is invalid because it is performed after an obligatory Prayer, i.e., the `Isha‘; hence, it is invalid before the `Isha‘ Prayer, just as is the sunnah Prayer following `Isha‘. Also, they say that the Tarawih Prayer is performed after the two rak`ahs of sunnah Prayer after the `Isha‘. Al-Majd, one of the Hanbali jurists, says, “As it is disliked to delay the Sunnah prayer of the `Isha‘ to be performed after the chosen time of the `Isha‘, it is more suitable to perform the Tarawih prayer following the Sunnah of the `Isha‘.”

If one performed it (i.e. the Tarawih) after the `Isha‘ Prayer and the Witr Prayer, many of the Hanafis hold the opinion that it is sufficient. Some of the Hanafis and Shafi`is say that it is preferable to delay the Tarawih Prayer until the third or the half of the night. The Hanafis differ concerning performing it after the half of the night: Some say that it is disliked, as it succeeds the `Isha‘ Prayer, just like the sunnah Prayer of the `Isha‘; and the right opinion that it is not disliked, as it is the Night Prayer that is preferable to be performed late at night. The Hanbalis say that it is preferable to  performTarawih in the early part of the night, as people used to do so during the time of `Umaribn Al-Khattab (may Allah be pleased with him). When Ahmad was asked to delay the Tarawih Prayer until the last part of the night, he answered, “The sunnah of the Muslims is dearer to me.”

It was mentioned in Al-Insaffi Al-Fiqh Al-Hanbali: According to the right opinion of the madhhab and the chosen opinion of the majority of the scholars, the time of the Tarawih Prayer is after the `Isha‘ Prayer and its sunnah Prayer. As reported and asserted by Harb in Al-`Umdah, Imam Ahmad
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Hanbal said that it is performed after the `Isha‘ and before the sunnah Prayer of the `Isha‘.

Also, it was stated in Kashshaf Al-Qina` fi Al-Fiqh Al-Hanbali, “If he prayed the Tarawih Prayer after the `Isha‘ Prayer and before itssunnah, it is absolutely valid; however, it is better to be performed after the sunnah Prayer.”