Numbers, Chapter 20. The picture above is from course material at Hope College, a college of the Reformed Church.
Once again the children of Israel kvetch to Moses. At 20:5 they say “it has no figs, no vines, no pomegranates, and there is not even water to drink!” God tells Moses to order the rock to give water (20:8). Moses and Aaron go there, and Moses strikes the rock twice (20:11).
God then punishes Moses and Aaron by telling them that they shall not enter into the promised land. The Jerusalem Bible footnotes that in Dt. 1:37 it is the abandonment of the Canaanite campaign that prompts this punishment.
At 20:14 we have a message to Edom. The Israelites ask for safe passage across the Edomite territory. They are rebuffed, and Israel turns away.
Beginning at 20:22 we have the account of the death of Aaron. Moses is told that Aaron must be gathered to his people (20:24). This sounds suspiciously like an order for execution. Aaron and his son go to Mount Hor with Moses, and Aaron is stripped of his garments, and the raiment is given to Aaron’s son.”Moses stripped Aaron of his garments and put them on Eleazar his son; and Aaron died there on top of the mountain” (20:28). So did Aaron die of exposure from being naked on the mountain top, or did he die a more violent death? The death happens after the semi-colon, but isn’t really described. A quick check of Wikipedia shows that most religious traditions regard Aaron’s death as being non-violent, or at least without active human intervention, i.e., death through exposure or something more benign. Britannica simply mentions that two different traditions are recorded for the death of Aaron.