‘And Yahweh said to Gideon, “The people who are with you are too many for me to give the Midianites into their hand, lest Israel vaunt themselves against me, saying, my own hand has saved me.” '
Gideon undoubtedly wondered whether his thirty two units would be sufficient. But Yahweh declared that they were too many. For He knew men's hearts. He did not want them taking the credit on themselves. This was in fact further assurance that He was committed to victory, and demonstrated that His strength did not lie in numbers but in His own power. Gideon could take comfort in that.
“Lest Israel vaunt themselves against Me.” The unusual use of ‘Israel' (unusual in Judges - see introduction) as the subject of an active verb stresses the theoretical nature of the idea being mooted. His covenant ‘children of Israel' would not vaunt themselves against Him, only a rebel Israel.