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.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
nasai-kubra:627 – Sūwayd b. Naṣr > ʿAbdullāh > Sufyān > Abū Ḥaṣīn > Abū ʿAbd al-Raḥman al-Salamī

" 'Umar said: 'The Sunnah is to hold the knees.'" (Using translation from Nasāʾī 1035)  

الكبرى للنسائي:٦٢٧ – أَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ قَالَ أَخْبَرَنَا عَبْدُ اللهِ عَنْ سُفْيَانَ عَنْ أَبِي حَصِينٍ عَنْ أَبِي عَبْدِ الرَّحْمَنِ السَّلَمِيِّ قَالَ

قَالَ عُمَرُ «إِنَّمَا السَّنَةُ الْأَخْذُ بِالرُّكَبِ»  

See similar narrations below:

Collected by Nasāʾī, Bayhaqī
nasai:1035 – Sūwayd b. Naṣr > ʿAbdullāh > Sufyān > Abū Ḥaṣīn > Abū ʿAbd al-Raḥman al-Sulamī

" 'Umar said: 'The Sunnah is to hold the knees.'"  

النسائي:١٠٣٥ – أَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ عَنْ سُفْيَانَ عَنْ أَبِي حَصِينٍ عَنْ أَبِي عَبْدِ الرَّحْمَنِ السُّلَمِيِّ قَالَ قَالَ

عُمَرُ إِنَّمَا السُّنَّةُ الأَخْذُ بِالرُّكَبِ  

bayhaqi:2547 – Abū ʿAbdullāh al-Ḥāfiẓ And ʾAbū Bakr b. al-Ḥasan al-Qāḍī > Abū al-ʿAbbās > al-Aṣam > Muḥammad b. Khālid b. Khalī > Aḥmad b. Khālid > Isrāʾīl > Abū Ḥuṣayn > Abū ʿAbd al-Raḥman al-Sulamī

" 'Umar said: 'The Sunnah is to hold the knees.'" (Using translation from Nasāʾī 1035)   

البيهقي:٢٥٤٧ – وَأَخْبَرَنَا أَبُو عَبْدِ اللهِ الْحَافِظُ وَأَبُو بَكْرِ بْنُ الْحَسَنِ الْقَاضِي قَالَا ثنا أَبُو الْعَبَّاسِ هُوَ الْأَصَمُّ ثنا مُحَمَّدُ بْنُ خَالِدِ بْنِ خَلِيٍّ ثنا أَحْمَدُ بْنُ خَالِدٍ ثنا إِسْرَائِيلُ عَنْ أَبِي حُصَيْنٍ عَنْ أَبِي عَبْدِ الرَّحْمَنِ السُّلَمِيِّ قَالَ كُنَّا إِذَا رَكَعْنَا جَعَلْنَا أَيْدِينَا بَيْنَ أَفْخَاذِنَا فَقَالَ

عُمَرُ ؓ إِنَّ مِنَ السُّنَّةِ الْأَخْذَ بِالرُّكَبِ