Literary Devices – Bemidbar 9

In the second half of Bemidbar 9, which focuses on the nation's journeying, this full phrase (with slight variations) comes up three times.  The individual roots “נסע” and “חנה” together appear a total of 15 times, and the phrase “עַל פִּי י״י” appears six times (verses 18, 20, 23). The repetition highlights how, at this stage of their journey, the people are still obedient, following Hashem’s instructions without question or complaint.  

The other keyword in the second half of the chapter is "ענן", cloud, whose rise and descent served as markers that it was time to travel.

• Watch Bemidbar: The Story of Two Generations, by Dr. Yael Ziegler, for discussion of the way in which the generation that left Egypt is depicted in the beginning of Bemidbar as obediently following Hashem’s words (as expressed by the keywords of this chapter), and how and why their behavior changes in the face of subsequent challenges. 
• See See Pillar of Fire, Pillar of Cloud, by R. Tamir Granot, for analysis of the phenomenon of Hashem’s revelation through natural phenomena such as fire and clouds. He suggests that in Tanakh, the cloud and pillar of fire are not two distinct modes of revelation, but one and the same. God's glory is manifest as fire which is screened by the cloud. It is referred to as one or the other due to the perception of the viewer, who might see fire at night, but only cloud during the day.