प्राकृतैर्वैकृतैर्यज्ञैर्द्रव्यज्ञानक्रियेश्वरम् ॥ ५१ ॥
prākṛtair vaikṛtair yajñair
īje — he worshiped; anu-yajñam — with each kind of sacrifice; vidhinā — by the proper regulations; agni-hotra — by offering oblations into the sacred fire; ādi — and so on; lakṣaṇaiḥ — characterized; prākṛtaiḥ — unmodified, completely specified by śruti injunctions; vaikṛtaiḥ — modified, adjusted according to the indications of other sources; yajñaiḥ — with sacrifices; dravya — of the sacrificial paraphernalia; jñāna — of the knowledge of mantras; kriyā — and of the rituals; īśvaram — the Lord.
Performing various kinds of Vedic sacrifice according to the proper regulations, Vasudeva worshiped the Lord of all sacrificial paraphernalia, mantras and rituals. He executed both primary and secondary sacrifices, offering oblations to the sacred fire and carrying out other aspects of sacrificial worship.
There are numerous kinds of Vedic fire sacrifice, each of which involves several elaborate rituals. The Brāhmaṇa portion of the Vedic śruti specifies the complete step-by-step procedure of only a few prototype sacrifices, such as the Jyotiṣṭoma and Darśa-pūrṇamāsa. These are called the prākṛta, or original, yajñas; the details of other yajñas must be extrapolated from the patterns of these prākṛta injunctions according to the strict rules of the Mīmāṁsā-śāstra. Since other yajñas are thus known by derivation from the prototype sacrifices, they are called vaikṛta, or “changed.”