كتاب المقدمات
The Book of Miscellany
(27)
Chapter: Reverence towards the Sanctity of the Muslims
(27)
- باب تعظيم حرمات المسلمين وبيان حقوقهم والشفقة عليهم ورحمتهم
Riyad as-Salihin 222
Abu Musa (May Allah bepleased with him) reported:
Messenger of Allah (ﷺ) said, "The relationship of the believer with another believer is like (the bricks of) a building, each strengthens the other." He (ﷺ) illustrated this by interlacing the fingers of both his hands.

[Al-Bukhari and Muslim].

وعن أبي موسى رضي الله عنه قال‏:‏ قال رسول الله صلى الله عليه وسلم ‏ "‏ المؤمن للمؤمن كالبنيان يشد بعضه بعضًا‏"‏ وشبك بين أصابعه ‏.‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏ ‏.‏
Reference : Riyad as-Salihin 222
In-book reference : Introduction, Hadith 222