Parmeshwar has given a command to perform a Yajna by saying ‘स्वाहा यज्ञं कृणोतन’॥
Manusmriti the first 'मानव धर्मशास्त्र' describes five type of yajya:
होमो दैवो बलिर्भौतो नृयज्ञोऽतिथिपूजनम्॥ 3/70
The पंचयज्ञ include Brahmayajna- teaching of Vedas, Pitrayajna - devoted to forefathers, Devyajna - devoted to the Deva, Bhootyajna - devoted to charity, and Atithiyajna - devoted to guests.
Om Namo Nārāyaṇaya