The word atithi literally means a + tithi (without date) and denotes a person or guest who arrives without prior intimation. Such a person, the atithi, is accorded great respect in Hindu culture. A common saying is that ‘atithi should be treated as divine’. An atithi who arrives before or after meal-time should not be sent away without being fed. Regardless of caste, the guest must be given food.
In Hindu tradition, atithi satkara (proper hosting of an
atithi) is considered a yajna. It is said that even if one lives on scattered
grains in the fields after harvest and offers penance in the midst of panchagni
(five fires), a guest still must be fed or else all virtuous deeds are
nullified.
According to Dharmashastra, the grihastha (householder) should
perform pancha-mahayajna daily. Duty towards atithi occupies a prominent place
among these five yajnas. Manu, the lawgiver, states that one should not start studying
Vedas without permission of an atithi, if one is present in the house.
In Katha Upanishad, Yama regrets his absence from home when
Nachiketa, an atithi, has to go without food. Yama hailed the atithi as a great
knower of knowledge and offered him a boon for each night he dwelt in his
house.