4.28 Tatha, similarly; apare, others; are dravya-yajnah, perfomers of sacrifices through wealth-those sacrificers who spend wealth (dravya) in holy places under the idea of performing sacrifices; tapo-yajnah, performers of sacrifices through austerity, men of austerity, to whom austerity is a sacrifice; [This is according to Ast.-Tr.] yogayajnah, performers of sacrifice through yoga-those to whom the yoga consisting in the control of the vital forces, withdrawal of the organs, etc., is a sacrifice; and svadhyaya-jnana-yajnah, performers of sacrifices through study and knowledge.
Sacrificers through study are those to whom the study of Rg-veda etc. accroding to rules is a sacrifice. And sacrificers through knowledge are those to whom proper understanding of the meaing of the scriptures is a sacrifice. Others are yatayah, ascetics, who are deligent; samsita-vratah, in following severe vows. Those whose vows (vratah) have been fully sharpened (samsita), made very rigid, are samsita-vratah. [Six kinds of sacrifices have been enumerated in this verse.]
Further,