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.
bayhaqi:2631Abū Bakr b. al-Ḥārith al-Faqīh > Abū Muḥammad b. Ḥayyān > Muḥammad b. Yaḥyá > Abū Kurayb > Muḥammad b. Ḥujr > Saʿīd b. ʿAbd al-Jabbār > ʿAbd al-Jabbār b. Wāʾil from his mother > Wāʾil b. Ḥujr

[Machine] I prayed behind the Messenger of Allah ﷺ, then I prostrated, and the first thing that touched the ground were his knees.  

البيهقي:٢٦٣١وَأَخْبَرَنَا أَبُو بَكْرِ بْنُ الْحَارِثِ الْفَقِيهُ أنبأ أَبُو مُحَمَّدِ بْنُ حَيَّانَ ثنا مُحَمَّدُ بْنُ يَحْيَى ثنا أَبُو كُرَيْبٍ ثنا مُحَمَّدُ بْنُ حُجْرٍ ثنا سَعِيدُ بْنُ عَبْدِ الْجَبَّارِ عَنْ عَبْدِ الْجَبَّارِ بْنِ وَائِلٍ عَنْ أُمِّهِ عَنْ وَائِلِ بْنِ حُجْرٍ قَالَ

صَلَّيْتُ خَلْفَ رَسُولِ اللهِ ﷺ ثُمَّ سَجَدَ وَكَانَ أَوَّلَ مَا وَصَلَ إِلَى الْأَرْضِ رُكْبَتَاهُ