Ganapathi related - How Kubera was humbled by Lord Ganapathi?

Kubera is the Lord of the North side with the capital of Alakaapuri and the Lord of wealth. He was a staunch devotee of Lord Siva and on his blessings only Kubera became what he was. Once Kubera visited the Lord Siva at Kailas. He saw that the Lord and his consort were living in place of snow without any roof over them and the place was surrounded by the snow clad mountains. He was scornful at the site and invited the lord to go over to his place where he will give him a warm welcome and feed him with 50 + delicious dishes. He thought that if the Lord comes to his place, he will know the difference between the facilities and comforts of the 2 places (lord's place and Kubera's place). The lord smiled to himself. But goddess Parvathy became very angry and said that we are not very particular about food but since you invited us with your devotion and love, I will send my son Ganesh (Ganapathy, Vinayak). Since he is fond of food he will be pleased. Accordingly Kubera with the Lord Ganesh and his vehicle mouse went in Kubera's Pushpak Viman (Kuber's plane) to Alakaapuri.

For the occasion of the feeding, all the VIP's of all the 14 lokas of the universe had come. The food items were delicious and flavored the aroma was making every body's mouth to water. As soon as Lord Vinayak reached Kuber's place he started telling about his hunger. Since Ganesh was a child they thought first let him be fed. Hundreds of dishes were kept in front of Ganesh for him to eat.Instantly Ganesh finished all the items given to him and informed that he is still hungry. Whatever food was prepared was finished and fresh preparations were also finished and still the hunger is not satisfied. Ganesh started to swallow the everything he could see around including the furniture of Kuber's palace in spite of Kuber's pleadings to spare. Kuber immediately flew to the Kailas and prostrated at the feet of Lord Siva and requested him to save. All his pride and ego vanished and he only wanted to save his skin.  The lord smiled to himself and gave Kuber a handful of 'Avil' (pounded and flattened rice flakes) and advised Kuber to give the same to Lord Ganesh. By the time he returned not only the palace but the entire city of Alakapuri has gone into the stomach of Lord Ganesha. Kuber gave the avil to Ganapthai and prostrated at the feet of Ganapathi and stood in front of the lord with folded hands and repentance for his pride and ego. Lord Ganesh took a bit of the avil of his father. Immediately his hunger was satisfied.

The essence is that one should not be unduly proud, elated or egoistic at gains and scorn others.