Deuteronomy 1:42

And the Lord said unto me
When the people had armed themselves, and were in motion, or ready to set forward to ascend the hill:

say unto them, go not up, neither fight;
neither go up the hill, and if they did, contrary to this order, and should meet with enemies, not fight them, but retreat:

for I am not among you:
the ark of the covenant, the symbol of his presence, was then among them, but it did not go with them, it continued in the camp, ( Numbers 14:44 ) nor did the Lord exert his power, or show himself present with them, or to be on their side, but left them to themselves, and to their enemies:

lest ye be smitten before your enemies;
God not being with them to fight for them, protect and defend them, and give them victory.