Is the word "Al-Azim" (The Mighty/Great) mentioned in the formula of seeking forgiveness about which the Prophet, peace and blessings be upon him, said: "He will be forgiven even if he had fled from the battlefield"?

A Muslim must preserve the wording of dhikr and supplications established by the Prophet, peace and blessings be upon him, without alteration. The word "al-Azim" (the Great) in the istighfar "Astaghfirullah alladhi la ilaha illa Huwa al-Hayy al-Qayyum wa atubu ilayh" (I seek forgiveness from Allah, there is no god but He, the Ever-Living, the Sustainer, and I repent to Him) is not authentically established in the sound hadiths reported in Sunan al-Tirmidhi and Mustadrak al-Hakim. It is most likely an insertion by some scribes.