פירוש על שמואל א 17:49

And he fell face downward. He should have fallen backwards since he had been struck on his forehead.²⁶The impact should have made him fall backwards. But, in order that Dovid should not be troubled to walk [the extra distance] and cut off his head, for Dovid now saved twelve amos and two zeres; for his height was six amos and a zeres, Dovid saved [walking] his entire height back and hs entire height forward.²⁷Another reason why he fell face downward is because ה׳ had decreed that the mouth that blasphemed shall lick the dust of the earth.