ישעיהו כב:ט פירוש: רש״י ואבן עזרא

the cracks of the city of David The cracks of the wall you saw that they had increased.

Ye have seen also, etc. They looked to the fortifications, and found that the breaches of the town of David were many; they were therefore obliged to collect the waters of the pool, that they might serve as a fence round the town.

and you gathered the water of the lower pool Jonathan renders: And you gathered the people to the waters of the lower pool, which is near the cracks of the city of David, to fight there, because you saw that Jerusalem had a weak spot there and was vulnerable to conquest from there.