✅Answer: Please consider the following narrations:

عَنْ عَلِیِّ بْنِ إِبْرَاهِیمَ عَنْ أَبِیهِ عَنْ عَبْدِ اللَّهِ بْنِ الْمُغِیرَةِ عَنْ مُعَاذِ بْنِ مُسْلِمٍ عَنْ أَبِی عَبْدِ اللَّهِ أَنَّهُ قَالَ لَا تَدَعْ أَنْ تَقْرَأَ بِقُلْ هُوَ اللَّهُ أَحَدٌ وَ قُلْ یَا أَیُّهَا الْکَافِرُونَ فِی سَبْعِ مَوَاطِنَ فِی الرَّکْعَتَیْنِ قَبْلَ الْفَجْرِ وَ رَکْعَتَیِ الزَّوَالِ وَ الرَّکْعَتَیْنِ بَعْدَ الْمَغْرِبِ وَ رَکْعَتَیْنِ مِنْ أَوَّلِ صَلَاةِ اللَّیْلِ وَ رَکْعَتَیِ الْإِحْرَامِ وَ الْفَجْرِ إِذَا أَصْبَحْتَ بِهَا وَ رَکْعَتَیِ الطَّوَافِ

📚Kafi, Vol. 3, p. 316

وَ فِی رِوَایَةٍ أُخْرَی أَنَّهُ یَبْدَأُ فِی هَذَا کُلِّهِ بِقُلْ هُوَ اللَّهُ أَحَدٌ وَ فِی الثَّانِیَةِ بِقُلْ یَا أَیُّهَا الْکَافِرُونَ إِلَّا فِی الرَّکْعَتَیْنِ قَبْلَ الْفَجْرِ فَإِنَّهُ یَبْدَأُ بِقُلْ یَا أَیُّهَا الْکَافِرُونَ ثُمَّ یَقْرَأُ فِی الرَّکْعَةِ الثَّانِیَةِ بِقُلْ هُوَ اللَّهُ أَحَدٌ

Translation: Imam Sadiq (AS) said: Do not neglect reciting the surahs 'Qul Huwa Allahu Ahad' and 'Qul Ya Ayyuha al-Kafirun' in seven places: in the Nafila of Fajr, the first two rakats of the Nafila of Dhuhr, the first two rakats of the Nafila of Maghrib, the first two rakats of the night prayer, the two rakats of the prayer of Ihram, in the Fajr prayer when it is fully morning (after the time has passed and the sky has brightened), and in the two rakats of Tawaf prayer.

Al-Kulaini (RA) says: In another narration, it is stated that in all these cases, recite 'Qul Huwa Allahu Ahad' in the first rak'ah after Al-Hamd, and 'Qul Ya Ayyuha al-Kafirun' in the second rak'ah after Al-Hamd, except in the Nafila of Fajr, where in the first rak'ah, after Al-Hamd, recite 'Qul Ya Ayyuha al-Kafirun', and in the second rak'ah after Al-Hamd, recite 'Qul Huwa Allahu Ahad'.

Note: The Imams (AS) have strongly emphasized the importance of all daily Nafila prayers, so we should not neglect performing them. InshaAllah.

اللَّهُمَّ صَلِّ عَلَی مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ عَجِّلْ لِوَلِیِّکَ الْفَرَجَ وَ الْعَافِیَةَ وَ النَّصْر