✅ Answer: Pay attention to the following narrations:

1 عَنْ زُرَارَةَ عَنْ أَبِي جَعْفَرٍ أَنَّهُ قَالَ: لَا تُعَادُ الصَّلَاةُ إِلَّا مِنْ خَمْسَةٍ الطَّهُورِ وَ الْوَقْتِ وَ الْقِبْلَةِ وَ الرُّكُوعِ وَ السُّجُودِ ثُمَّ قَالَ الْقِرَاءَةُ سُنَّةٌ وَ التَّشَهُّدُ سُنَّةٌ وَ لَا تَنْقُضُ السُّنَّةُ الْفَرِيضَةَ.

📚 Al-Faqih, Vol. 1, p. 339

Imam Baqir, peace be upon him, said: The prayer is not to be repeated except for five things: ritual purity (wudu or ghusl or tayammum), time, qiblah, bowing, and prostration.

Then he said: Recitation is a sunnah (tradition), and tashahhud is a sunnah, and a sunnah does not invalidate a fard (obligatory duty)!

2 عَنْ سُفْيَانَ بْنِ السِّمْطِ عَنْ أَبِي عَبْدِ اللَّهِ قَالَ: تَسْجُدُ سَجْدَتَيِ السَّهْوِ فِي كُلِّ زِيَادَةٍ تَدْخُلُ عَلَيْكَ أَوْ نُقْصَانٍ.

📚 Al-Tahdhib, Vol. 2, p. 155

Imam Sadiq, peace be upon him, said: For every increase or decrease that occurs to you, you perform two prostrations of forgetfulness!

✅ Qunut is mentioned in narrations as an obligatory sunnah in prayer, and you can see the narrations related to it in the following link:

https://feghh14.com/en/1238

✅ However, according to the general principle mentioned at the end of narration 1 , unintentional error in a sunnah, whether an unintentional increase or an unintentional decrease in a sunnah, does not invalidate or require the repetition of the obligatory prayer. Since, according to the narrations in the above link, qunut is considered a sunnah or an obligatory sunnah, an unintentional increase of one qunut in the prayer does not invalidate the prayer, and the prayer continues and is correct and valid. However, to act upon narration 2 , because of the addition of an extra qunut by the worshipper, he should perform two prostrations of forgetfulness after the salutation of the prayer, and nothing else has been required of him.

اللَّهُمَّ فَصَلِّ عَلَی مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ عَجِّلْ لِوَلِیِّکَ الْفَرَجَ وَ الْعَافِیَةَ وَ النَّصْرَ