2 Samuel 5:6-8

6Now the king and his soldiers marched to Jerusalem against the Jebusites, the inhabitants of the region. But they said to David, “You’ll never get in here! Even the blind and the lame could ward you off,” thinking, “David can’t get in here.”

7Nevertheless, David did capture the stronghold of Zion (that is, the City of David).

8On that day David said, “Whoever would conquer the Jebusites must strike through the water shaft to those ‘lame and blind’ whom David’s soul despises.” That is why they used to say, “The blind or lame couldn’t get into the house.”