Like bricks in a wall
الْمُؤْمِنُ لِلْمُؤْمِنِ كَالْبُنْيَانِ يَشُدُّ بَعْضُهُ بَعْضًا
Al-mu'minu li-l-mu'mini ka-l-bunyani yashuddu ba'duhu ba'da.
"A believer to a believer is like a single structure, one part supporting the other."
Narrated by Abu Musa al-Ash'ari. Sahih al-Bukhari 481, Sahih Muslim 2585
A short reflection
The Prophet ﷺ interlocked his fingers as he said it. No believer stands alone, you're holding up someone, someone is holding up you.