Dhanvantari Trayodashi (धन्वंतरि त्रयोदशी)

Dhanvantari Trayodashi (धन्वंतरि त्रयोदशी) is celebrated on the thirteenth day (त्रयोदशी) of the waning moon in the month of Kartik, two days before the festival of Deepavali. On this day, Dhanvantari, the incarnation of Lord Vishnu (Bhagwat Puraan, 2.7.21) is worshipped. Dhanvantari Trayodashi is popularly known as Dhanteras (धनतेरस) and probably that is why it is associated with material wealth (धन) and expensive items like gold. There is a tradition of shopping gold jewelry and other expensive ornaments and utensils on Dhanteras but there is little evidence that these are related to Dhanvantari. He is considered to be the purveyor of Ayurveda (Sushrut Samhita) and the provider of good health rather than material wealth.

By Dhanwantari4u - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=64079697

According to Dhanvantari Strotram (origin unknown), Dhanvantari has four hands holding a conch (शंख), a disc like weapon (चक्र), a pot of nectar (अमृत कलश) and a leech (जोंक). Although leech is ordinarily a blood sucking worm, certain varieties of leeches have been used for medical purposes, especially in controlling blood circulation and surgery. Depiction of leech in Dhanvantari's hand is an indication of his prowess in the field of medicine. Sometimes, medicinal plants are shown in his hand instead of a leech.

According to Vishnu Puraan (1.9.98), white robed Dhanvantari appeared during the great churn of the primordial ocean (समुद्र मंथन) with a pot of nectar (अमृत कमण्डल) in hand. In a later incarnation (Vishnu Puraan, 4.8.7-10), a son named Dhanvantari was born to Kashya (काश्य), the ruler of Kashi (काशिराज). This incarnation of Dhanvantari was ordained in an earlier birth by Lord Vishnu to divide the Ayurveda into eight parts and to be the receiver of the offerings made through the sacred fires (यज्ञ). It is this Dhanvantari who imparted the knowledge of Ayurveda to his disciple Sushrut (Sushrut Samhita).