An atithi or a guest has to be treated as if he is a god. Thus states the Taittirīya Upaniṣad (1.11).
Honouring guests and elders as also holy persons has been a bounden duty, especially for the gṛhastha or the householder.
Madhuparka is an important item offered to such guests. It may be prepared out of three materials (curds, honey and ghee) or five (curds, honey, ghee, water and ground grain or sugar).
In the earliest days, flesh was one of these five items, but seems to have been given up later when flesh-eating came to be abhorred.
The persons to whom madhuparka has to be offered, especially when they come to one’s house, are: ṛtvik (Vedic priest), ācārya (preceptor), bride-groom (during marriage), snātaka (a student of Vedic studies who has just graduated) and a king.
Elaborate rules have been given in the smṛtis as to the mode of offering madhuparka and also in receiving and consuming it (vide Āśvalāyana Gṛhya-sūtras 1.24.5-26).
The Kauśikasūtras (92) dealing with the gṛhya rites mentions nine kinds of mixtures as fit to be offered like madhuparka.
For instance the brāhma mixture has honey and curds; the aindra, pāyasa (pudding) only; saumya, curds and ghee; vāruṇa, water and ghee and so on. These mixtures seem to be offered during certain Vedic sacrifices like Rājasūya and Sautrāmaṇi.