John Gill Commentary Joshua 8:6

"and they will come out after us, till we have drawn them away from the city; for they will say, They flee before us, as at the first: so we will flee before them;" — Joshua 8:6 (ASV)

For they will come out after us
Of which there could be no doubt, when they should see them run from them:

till we have drawn them from the city ;
some distance from it, that they could not return soon enough to save it from the ambush, or prevent their entrance into it, and burning it:

for they will say, they will flee before us, as at the first ;
they run away as they did before, and let us pursue them and smite them as we did then:

therefore we will flee before them ;
to draw them out of the city, and make your way easy to get into it,