Once there was a village with very fertile soil. Farmers only had to scatter rice seeds into the paddy fields, and it would grow on its own. As the farmers had nothing else to do, they gathered at a carpenter's workshop to chat every day. The carpenter's name was Mo Dou, and he could not concentrate on his work because the farmers were too noisy. So, he handed his apprentice a magical bag of sawdust. He told the apprentice to go to the paddy fields each morning, and scatter a little pinch of sawdust. This would make weeds grow in the paddy fields, and keep the farmers busy. Alas! The apprentice was too lazy to scatter sawdust in the paddy fields each morning, so, he poured the whole bag of sawdust onto the field instead. In the end, the paddy fields were overgrown with weeds, and all the rice withered and died.

Mo Dou saw the trouble that his apprentice caused, and turned him into a cow as punishment. He ordered the cow to help the farmers till the fields and get rid of the weeds. However, even after turning into a cow, the apprentice continued to be lazy. When asked to till the fields, he would say, “I am too tired today!” Or, “I am too hungry to work!” The lazy cow was so full of excuses that Buddha decided to teach him a lesson. He drove a nail into the cow's chin to stop the cow from complaining. After that, the cow could only work hard. Till today, you can still see a nail-like bump on the cow's chin.

Since cows love to eat glutinous rice balls, people made the day of the winter solstice The cow's birthday. On that day, they would feed the cows glutinous rice balls, and glue a round nail on its horns and forehead. Also, to thank the cows for their hard work throughout the year, they let them rest on the day of the winter solstice.

從前有個村子，村裡的土壤十分肥沃，農夫只要將稻種撒到田裡，就可以坐著等收成。這些農夫們沒事做，每天都聚在一位叫墨斗公的木匠店裡聊天。墨斗公被這些農夫吵得根本無法工作，於是他就交給徒弟一包施過法的鋸木屑，並交待徒弟每天早上到農田裡撒一小撮，讓農田長出雜草，這樣農夫就會勤勞下田耕作。誰知道徒弟嫌每天撒太費事，竟然一口氣把整包鋸木屑都倒光，結果，所有的農田長滿雜草，稻子也全部枯死。

墨斗公看到自己的徒弟闖下大禍，就罰他變成一頭牛，幫農夫耕田除草。沒想到徒弟變成牛後，懶惰的本性不改，要牠耕田，牠就說出：「今天我太累了」、「不餵我吃東西，怎麼工作？」等等許多藉口。天上的佛祖看不下去，便在牛的下巴釘了一根釘子，讓牠無法開口抱怨，只能認真的工作，到現在牛的下巴還有一顆突起像痣的東西。

由於牛很愛吃湯圓，後來人們就把冬至這天作為「牛」的生日。在冬至這一天，人們除了餵牠湯圓外，還會在牛角、額頭上都粘上一顆「圓仔釘」，另外，為感謝牛一年來的辛勞，則讓牠舒舒服服的休息一天。