I went after him and struck him and delivered it out of his mouth. And if he arose against me, I caught him by his beard and struck him and killed him.
David is at length presented to Saul for his champion (Sa1 17:31) and he bravely undertakes to fight the Philistine (Sa1 17:32): Let no man's heart fail because of him. It would have reflected too much upon the valour of his prince if he had said, Let not thy heart fail; therefore he speaks generally: Let no man's heart fail.
Commenting on 1 Samuel 17:31-39
And I went out after him,.... Whether a lion or a bear; but mention after being made of his beard, a lion rather is meant: and smote him; with his fist, or rather with his shepherd's staff: and delivered it out of his mouth; snatched it out from thence, or obliged him to drop it, by beating him: and when he arose against me; after...
The slaying of the lion and the bear mentioned here, must have taken place at two different times; perhaps the verse should be read thus: I went out after him, (the lion). and smote him, etc. And when he (the bear) rose up against me, I caught him by the beard and slew him.