Ramban on Exodus 32:26/רמב"ן על שמות ל״ב:כ״ו

1AND MOSES STOOD IN THE GATE OF THE CAMP. This is connected with what is said in the preceding verse, thus stating that when Moses saw that the people would be a source of derision and disgrace amongst their enemies, and would thereby profane the Name of G-d, he stood in the gate of the camp and called out loudly, Whoso is on the Eternal’s side, let him come unto me; and they killed publicly all those who worshipped the calf, so that the matter be heard about amongst their enemies, and G-d’s Name would thus be sanctified, in place of the profanation that they had caused.