✅ Answer: Consider the following narration:

عَنْ حَمَّادِ عَنْ زُرَارَةَ قَالَ أَبُو جَعْفَرٍ السُّجُودُ عَلَی سَبْعَةِ أَعْظُمٍ الْجَبْهَةِ وَ الْکفین وَ الرُّکْبَتَیْنِ وَ الْإِبْهَامَیْنِ مِنَ الرِّجْلَیْنِ وَ تُرْغِمُ بِأَنْفِکَ إِرْغَاماً أَمَّا الْفَرْضُ فَهَذِهِ السَّبْعَةُ وَ أَمَّا الْإِرْغَامُ بِالْأَنْفِ فَسُنَّةٌ

📚 Khisal, Vol. 2, Page 349

Translation: Imam Baqir (AS) said: Prostration is performed on seven bones: the forehead, both palms, both knees, and the two big toes. You should also place your nose on the ground, but the obligatory part consists of these seven, while placing the nose on the ground is a recommended act (sunnah).

✅ In Shia narrations, like the one above, the placement of the two big toes on the ground during sujood is specified. We are required to ensure that only the tips of the big toes touch the ground.

However, if someone’s other toes also touch the ground, there is no narration stating that this invalidates the prayer, but we are obligated to follow the prescribed ruling.