Dhanteras Puja is also known as Dhantrayodashi. This festival is celebrated on Krishna Trayodashi of Kartik month. There is also Dhanvantari Trayodashi or Dhanvantari Jayanti on the day of Dhanteras. It is also celebrated as the birthday of the god of Ayurveda. Ganesh Lakshmi is brought home on this day. The decoration of Diwali in the houses also starts from this day. On this day, after cleaning the houses, making a Rangoli, lighting a lamp during the evening, Lakshmi is called.
The importance of Dhanteras has been explained in Hindu scriptures. According to Hindu calendar, on the day of Dhanteras, in the auspicious time, bringing new things in the house and worshiping Goddess Lakshmi and Kubera Ji removes the poverty and replenishes the storehouses of wealth. By buying gold, silver, brass and metals utensils etc. on Dhanteras, the way of progress opens and the bad energy is eliminated. Brass is the metal of Maharishi Dhanvantari. Not only this, Dhanteras is also celebrated as National Ayurveda Day. Deepotsav begins at Dhanteras. In the Jain Agam, Dhanteras is called 'Dhanya Teras' or 'Dhyan Teras'. According to Jain belief, Lord Mahavira went for meditation on this day and after three days of meditation, he did Nirvana (Moksha) on the day of Diwali. Since then, the day of Dhanteras is famous in Jain Agam as Dhanya Teras.
Dhanteras is celebrated on the day of Kartik month Trayodashi. Lord Dhanvantari was born on the day of Trayodashi of Krishna Paksha of Kartik month. Hence, the festival of Dhanteras started being celebrated on this day. Actually, during the churning of the ocean for nectar, Dhanvantari appeared with the nectar urn, so it is a tradition to buy utensils on the day of Dhanteras. Two days after the incarnation of Lord Dhanvantari, Mata Lakshmi had appeared with the Amrit Manthan, so the festival of Diwali is celebrated two days after Dhanteras.
On this day, Yamraj, the god of death, is worshiped. This is the only day in the year when Yamraj is worshiped. This puja is not performed during the day but at night, a lamp is lit for Yamraj.
On this day, a lamp of flour for Yama is made and kept at the main door of the house. This lamp is called Jamadiva i.e. Yamraj's lamp.
In the night, the women of the house light four lamps by putting oil in the lamp and making new cotton light. The lamp light should be kept towards the south direction.
Women worship Yama by lighting lamps including water, roli, flowers, rice, jaggery, Naivedhya etc. Since this lamp is lit for the god of death, Yama, the devotees should bow to him with full devotion while lighting the lamp, as well as pray that they maintain compassion for your family and nobody dies prematurely.