John Gill Commentary Joshua 23:10

"One man of you shall chase a thousand; for Jehovah your God, he it is that fighteth for you, as he spake unto you." — Joshua 23:10 (ASV)

One man of you shall chase a thousand
Here Kimchi and Ben Melech observe, that the future tense is put for the past, and that the sense is, one of them had chased a thousand in their war with the Canaanites; but Abarbinel disapproves of this observation, and thinks it refers to time to come, what they should be able to do if they cleaved unto the Lord; this was fulfilled in Samson, (Judges 15:15) ; such a promise was made, (Leviticus 26:8) ;

for the Lord your God he [it is] that fighteth for you ;
and no wonder then that a thousand should be put to flight by one man; the Targum interprets it of the Word of the Lord, as in (Joshua 23:3) ;

as he has promised you ;
see (Deuteronomy 1:30) (3:22) .