knightly deed

As I love God, 'tis a splendid idea, a real knightly deed!

"It was not a knightly deed," said Volodyovski, harshly.

Full many a knightly deed was wrought, and when fortune seemed to forsake the side of Satyrane, he himself was ever ready to assist his knights and uphold their honour, proving once again his far-famed prowess.

I never heard of his gallant steed, and there is no trace of his knightly deed!”

What knightly deed was done by three captains of David?