Wisdom 18:5

5 And when they had determined to slay the babes of the saints, one child being cast forth, and saved, to reprove them, thou tookest away the multitude of their children, and destroyedst them altogether in a mighty water.

Wisdom 18:5 In-Context

3 Instead whereof thou gavest them a burning pillar of fire, both to be a guide of the unknown journey, and an harmless sun to entertain them honourably.
4 For they were worthy to be deprived of light and imprisoned in darkness, who had kept thy sons shut up, by whom the uncorrupt light of the law was to be given unto the world.
5 And when they had determined to slay the babes of the saints, one child being cast forth, and saved, to reprove them, thou tookest away the multitude of their children, and destroyedst them altogether in a mighty water.
6 Of that night were our fathers certified afore, that assuredly knowing unto what oaths they had given credence, they might afterwards be of good cheer.
7 So of thy people was accepted both the salvation of the righteous, and destruction of the enemies.

The Brenton translation of the Septuagint is in the public domain.