Gideon's apprehension doth not seem to have arisen from fear of offence, in that he did it by night; but for fear of interruption, he wished to accomplish the divine command, and therefore did it perhaps the same night. He well knew the consequence of the people's displeasure, but which it should seem he did not fear.
Related Commentaries of Judges 6:26
Judges 6:26-27
26 And build an altar unto the LORD thy God upon the top of this rock,h in the ordered place, and take the second bullock, and offer a burnt sacrifice with the wood of the grove which thou shalt cut down.
27 Then Gideon took ten men of his servants, and did as the LORD had said unto him: and so it was, because he feared his father's household, and the men of the city, that he could not do it by day, that he did it by night.