✅Answer: Please pay attention to the following narrations:

1 مُحَمَّدُ بْنُ عَلِيِّ بْنِ الْحُسَيْنِ بِإِسْنَادِهِ عَنِ الْحَلَبِيِّ أَنَّهُ سَأَلَ أَبَا عَبْدِ اللَّهِ عَنِ الرَّجُلِ يَحْتَكُّ وَ هُوَ فِي الصَّلَاةِ قَالَ لَا بَأْسَ.

📚 Faqih, Vol. 1, p. 368

Translation: Halabi asked Imam Sadiq (peace be upon him) about a person who scratches his body while he is in prayer; the Imam said: There is no problem.

2 عَبْدُ اللَّهِ بْنُ جَعْفَرٍ فِي قُرْبِ الْإِسْنَادِ عَنْ عَبْدِ اللَّهِ بْنِ الْحَسَنِ عَنْ جَدِّهِ عَلِيِّ بْنِ جَعْفَرٍ عَنْ أَخِيهِ قَالَ: سَأَلْتُهُ عَنِ الرَّجُلِ يَكُونُ رَاكِعاً أَوْ سَاجِداً فَيَحُكُّهُ بَعْضُ جَسَدِهِ هَلْ يَصْلُحُ لَهُ أَنْ يَرْفَعَ يَدَهُ مِنْ رُكُوعِهِ أَوْ سُجُودِهِ فَيَحُكَّ مَا حَكَّهُ قَالَ لَا بَأْسَ إِذَا شَقَّ عَلَيْهِ أَنْ يَحُكَّهُ وَ الصَّبْرُ إِلَى أَنْ يَفْرُغَ أَفْضَلُ.

📚 Qurb al-Isnad, p. 88

Translation: Ali ibn Ja'far said: I asked Musa ibn Ja'far (peace be upon him): A person is in ruku' (bowing) or sujud (prostration) and a part of his body becomes itchy, is it appropriate for him to lift his hand from ruku' or sujud and scratch the itchy part? The Imam said: There is no problem for him to scratch it if it becomes difficult for him, but it is better to be patient until he finishes the prayer.

✅ It is observed that, although permission to scratch the body when it becomes itchy has been given, in the second hadith, it is considered more virtuous and better to be patient until the prayer is finished.