Commentary for Numbers 16:27

יצאו נצבים [AND DATHAN AND ABIRAM] CAME OUT, STATIONING THEMSELVES [AT THE ENTRANCE OF THEIR TENT] — The word נצבים suggests that they stood with erect stature in a challenging attitude, ready to revile and to curse. The phrase is similar in meaning to (I Samuel 17:16) “And he stationed himself (ויתיצב) there for forty days”, which occurs in the story of Goliath (Midrash Tanchuma, Korach 3).

ויעלו מעל קרח ודתן ואבירם, They lifted themselves up from the residence of Korach, etc. The effrontery of Datan and Aviram in continuing to maintain a defiant posture though they had already been abandoned by their fellow travelers who had withdrawn in fear of being punished together with them, made a suitable impression on Moses so that he announced that the people would witness Divine intervention by the manner in which these people were going to die. This was to prove that he had not appointed himself as their leader but that G'd had appointed him at the time. The words את כל המעשים האלה mean that everything Moses had done including insignificant appearing things were all carried out at G'd's instruction. He now said that not only would these people die immediately but they would die a particularly gruesome death.

With haughty bearing. Rashi is answering the question: What is meant by “went out and stood”? It is obvious that they did not go out while sitting! (Re’m). There is another question: What is meant by “went out and stood”? The word “went out” implies that they were moving, while the word “stood” implies that they were still. Rashi answers this question by explaining “to revile and blaspheme…”