While not explicitly about brothers

[Mary Naeem]

Psalm 127:5


"Blessed is the man who fills his quiver with them! He shall not be put to shame when he speaks with his enemies in the gate."

Reflection: While not explicitly about brothers, this verse suggests that having many sons (or brothers) is a blessing and source of strength.
The Bible is full of verses that emphasize the importance of family and the support that comes from having siblings. In addition to the verse mentioned, there are many others that speak to the value of familial relationships. For example, there are several bible verses on adultery that warn against the destruction it can cause to not only a marriage, but also to the entire family unit. The strong bonds between brothers and the importance of family unity are recurring themes throughout the Bible.