Chukat - Chamishi
The Death of Aharon
The nation traveled from Kadesh to a mountain called Hor. G-d said that Aharon's time was up. Moshe was to take Aharon and Aharon's son Elazar up the mountain. There, he was to divest Aharon of his special High Priest clothes and place them on Elazar. After this, Aharon would be "gathered to his people."
The three went up the mountain but only two came down. When the people saw this, they realized that Aharon had died. He was so beloved by the people that they mourned him a full month.
The king of Arad heard that Israel was traveling by, so he attacked them and took prisoners. The Jews prayed to G-d that if He enabled them to defeat this foe, they would consecrate the spoils. He granted this request and the Jews called the city the conquered Charma, from the word cheirem. (Again, see parshas Bechukosai, Leviticus chapter 27, for more about cheirem.)
As the Jews circled around Edom, they became disheartened and started to complain again. This time, it was not a valid complaint; they grumbled that the manna G-d had given them was insubstantial. (The manna left no waste product. This was a blessing, but they turned it into a criticism.) G-d responded by sending poisonous snakes to bite the complainers, who started to die. As usual, they turned to Moshe for help.
Moshe prayed and G-d responded. He told Moshe to make a copper snake and place it on a tall pole. When someone was bitten by a snake, they would look at this image and live. (Later, the Jews came to worship this snake as an idol, so it was destroyed by King Chizkiyahu. See 2 Kings chapter 18. That the rabbis approved of this action can be seen in Talmud Pesachim 56a.)