Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
ahmad:3305Yazīd > Ibn Abū Dhiʾb > Shuʿbah > Raʾá Ibn ʿAbbās a man Sājid Qad Ābtasaṭ Dhirāʿayh

[Machine] Ibn Abbas said, "This is how a dog stretches." I saw the Messenger of Allah ﷺ when he prostrated, I saw the whiteness of his armpits.  

أحمد:٣٣٠٥حَدَّثَنَا يَزِيدُ أَخْبَرَنَا ابْنُ أَبِي ذِئْبٍ عَنْ شُعْبَةَ قَالَ رَأَى ابْنُ عَبَّاسٍ رَجُلًا سَاجِدًا قَدِ ابْتَسَطَ ذِرَاعَيْهِ فَقَالَ

ابْنُ عَبَّاسٍ هَكَذَا يَرْبِضُ الْكَلْبُ رَأَيْتُ رَسُولَ اللهِ ﷺ إِذَا سَجَدَ رَأَيْتُ بَيَاضَ إِبْطَيْهِ