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.
abudawud:758Musaddad > ʿAbd al-Wāḥid b. Ziyād

(The established way of folding hands is) to hold the hands by the hands in prayer below the navel. Abu Dawud said: I heard Ahmad b. Hanbal say: The narrator 'Abd al-Rahman b. Ishaq al-Kufi is weak (i.e. not reliable).  

أبو داود:٧٥٨حَدَّثَنَا مُسَدَّدٌ حَدَّثَنَا عَبْدُ الْوَاحِدِ بْنُ زِيَادٍ عَنْ عَبْدِ الرَّحْمَنِ بْنِ إِسْحَاقَ الْكُوفِيِّ عَنْ سَيَّارٍ أَبِي الْحَكَمِ عَنْ أَبِي وَائِلٍ قَالَ قَالَ

أَبُو هُرَيْرَةَ أَخْذُ الأَكُفِّ عَلَى الأَكُفِّ فِي الصَّلاَةِ تَحْتَ السُّرَّةِ  

قَالَ أَبُو دَاوُدَ سَمِعْتُ أَحْمَدَ بْنَ حَنْبَلٍ يُضَعِّفُ عَبْدَ الرَّحْمَنِ بْنَ إِسْحَاقَ الْكُوفِيَّ

See similar narrations below:

Collected by Aḥmad
ahmad:875ʿAbdullāh > Muḥammad b. Sulaymān al-Asadī Lūwayn > Yaḥyá b. Abū Zāʾidah > ʿAbd al-Raḥman b. Isḥāq > Ziyād b. Zayd al-Suwāʾī > Abū Juḥayfah > ʿAlī

Part of the Sunnah in prayer is to put one hand over the other beneath the navel.  

أحمد:٨٧٥حَدَّثَنَا عَبْدُ اللهِ حَدَّثَنَا مُحَمَّدُ بْنُ سُلَيْمَانَ الْأَسَدِيُّ لُوَيْنٌ حَدَّثَنَا يَحْيَى بْنُ أَبِي زَائِدَةَ حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ إِسْحَاقَ عَنْ زِيَادِ بْنِ زَيْدٍ السُّوَائِيِّ عَنْ أَبِي جُحَيْفَةَ عَنْ عَلِيٍّ قَالَ

إِنَّ مِنَ السُّنَّةِ فِي الصَّلاةِ وَضْعُ الْأَكُفِّ عَلَى الْأَكُفِّ تَحْتَ السُّرَّةِ