The following is from the Shlah HaKadosh
?? ???? ?????, ???? ????? ???? ????; ???? ????, ???????. ?? ????, ???
The Shlah offers a slightly different interpretation than Rashi. ??, meaning, ??, If you say in your heart (and kudos for being truthful) that since the enemy is greater, therefore there is no way to defeat them Derech HaTeva (naturally), thus I, Hashem, promise you victory, ?? ????, ???. Hashem will assist.
However, If you come with the feeling ???? ????? ??? ??? ?? ?? ???? ???, Then you have reason to be fearful.