Sahih al-Bukhari 481
Sahih al-Bukhari · Book 8: Prayers (Salat) · To clasp one's hands by interlocking the fingers in the mosque or outside the mosque
Narrated Abu Musa:
حَدَّثَنَا خَلاَّدُ بْنُ يَحْيَى ، قَالَ حَدَّثَنَا سُفْيَانُ ، عَنْ أَبِي بُرْدَةَ بْنِ عَبْدِ اللَّهِ بْنِ أَبِي بُرْدَةَ ، عَنْ جَدِّهِ ، عَنْ أَبِي مُوسَى ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِنَّ الْمُؤْمِنَ لِلْمُؤْمِنِ كَالْبُنْيَانِ، يَشُدُّ بَعْضُهُ بَعْضًا ". وَشَبَّكَ أَصَابِعَهُ.
The Prophet (ﷺ) said, "A faithful believer to a faithful believer is like the bricks of a wall, enforcing each other." While (saying that) the Prophet (ﷺ) clasped his hands, by interlacing his fingers.