Judges 20:17
And the men of Israel, beside Benjamin, were numbered four hundred thousand men that drew sword: all these were men of war.
Cross-reference
Judges 20:2
Parallel
Judges 20:2 gives the same figure of 400,000 swordsmen for Israel's army — confirming the size of the force gathered here.
Hosea 10:9
Allusion
Hosea 10:9 recalls the sin of Gibeah, the event that led to the military census and civil war here.