Abu Musa reported that the Prophet ﷺ said, "A believer to another believer is like a building, each part strengthening the other." Then he interlaced his fingers.
ى، عن النبي ﷺ قال: المؤمن للمؤمن كالبنيان يشد بعضه بعضا. وشبك بين أصابعه.
Bukhari narrated it in the Book of Wrongs (2446), and Muslim in the Book of Righteousness and Maintaining Ties (2585), both of them through the route of Buraid, from Abu Burda, from Abu Musa, and he mentioned it. The wording is Bukhari's, and Muslim did not mention the interlacing of the fingers.