Question: Does one have to repeat their prayer if they make a mistake in recitation such as saying kul in place of qul? Is it permissible to say, in the sitting between the two prostrations, the supplication ‘rabbi ghifirli – My Lord, forgive me.”?
Answer:
In the Name of Allah, the Most Merciful and Compassionate
To answer your first question, the answer is no. You do not have to repeat your prayer.
Mistakes in Recitation
Even though one should not take the correct recitation of the Qur’an lightly – one’s prayer is valid even if they make errors in their recitation. This is due to the widespread lack of proficiency amongst the people in reciting the Qur’an. [Ibn ‘Abidin, Radd al-Muhtar]
Supplicating Between the Two Prostrations
Regarding your second question – it is permissible for you to make the above-mentioned supplication.
Scholars have deemed the supplication between the two prostrations to be a good act. What one says in this supplication is up to them; scholars have put forth suggested supplications – such as the one you have mentioned – which one is welcome to use. [Tahtawi/Shurunbulali, Hashiyat Maraqi al-Falah]
I hope this helps,
Allah knows best.
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani