It is recommended that in the Friday prayer, and in ṣubḥ, ẓuhr, and ʿaṣr prayers on Friday, and in ʿishāʾ prayers on Thursday night, one should recite Sūrat al-Jumuʿah in the first rakʿah after Sūrat al-Ḥamd, and Sūrat al-Munāfiqūn in the second rakʿah after Sūrat al-Ḥamd. If a person begins reciting one of these surahs in prayers on Friday, then based on obligatory precaution, he cannot leave it and recite another surah.
Ruling 974.* If after Sūrat al-Ḥamd one begins reciting Sūrat al-Ikhlāṣ or Sūrat al-Kāfirūn, he cannot leave it and recite another surah instead. This rule applies to the nāfilah prayers as well based on obligatory precaution.
However, in the Friday prayer and the prayers on Friday, if one forgetfully recites one of these two surahs instead of Sūrat al-Jumuʿah and Sūrat al-Munāfiqūn, he can leave it and recite Sūrat al-Jumuʿah and Sūrat al-Munāfiqūn instead; however, the recommended precaution is that one should not leave it [i.e. Sūrat al-Ikhlāṣ or Sūrat al-Kāfirūn] after having recited half of it.