In prostration, place your palms on the ground level with your shoulders, keep the fingers together facing the qiblah, and raise your forearms off the ground and away from your sides — the Prophet ﷺ would keep them so raised “that the whiteness of his armpits could be seen,” and forbade spreading them like a dog. (al-Bukhārī & Muslim).
العربية: عن أبي حميد الساعدي رضي الله عنه: «فإذا سجد وضع يديه غير مُفترشٍ ولا قابضهما، واستقبل بأطراف أصابع رجليه القبلة». (البخاري). وعن ميمونة رضي الله عنها: «كان ﷺ إذا سجد جافى حتى يُرى مَن خلفه وَضَح إبطيه». (مسلم).
In sujūd, palms by the shoulders, fingers together toward the qiblah, forearms raised off the ground.