The long Dua made after recitation of Qur'an in Taraweeh of 27th of Ramadhan
Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
We do not know any authentic Hadith that proves a given Du'a in prayer after completing the recitation of the Qur'an. It is reported from Anas Ibn Malik that he used to gather his family members when he finishes the recitation of the whole Qur'an and make Du'a. But it was outside of the prayers not during them.
Some scholars are of the opinion that it is allowed; Imam Ahmed is one of them.
Hanbal said: " I heard Imam Ahmed saying: "If you finish reciting the last chapter of the Qur'an, raise your hands for Du'a before making Ruku. He was asked the support for his opinion; he said: "I saw the people of Makkah doing so, and Sufyan Ibn Uyainah was doing the same with them."
Al Abbas Ibn Abdul Azeem said:" we found the people of Al Basra, Makkah and others do it, and it is also reported from Othman ibn Affan ( may Allah pleased with him). Hence some scholars considere it likeable since it had been practiced without any objection from Muslims."
Other scholars are of the opinion that it is not correct to do so since it is not reported from the prophet nor from his companions.
However, the matter is tolerable. Sheikh Ibn Othaymin said:" We should not call it Bid'ah since the scholars of Sunnah have different opinions regarding this matter."
However, we draw the attention of our brothers that lengthening Dua so that it becomes hard for the people to follow it is not allowed since the prophet ordered us to make the prayers easy for the people. Similarly this Dua should not made long as to avoid boring people and causing hardship.
Know that the Hujjah (source of religion) is only the Quran, Hadith and the concensus of Shariah.
So, the practice of a given person cannot be considered a source of religion.
Allah knows best.
Fatwa answered by: The Fatwa Center at Islamweb