Yuga-Vibhāga and Kāla-Pramāṇa
Measures of Time and the Four Yugas
आरंभयज्ञाः क्षत्राश्च हविर्यज्ञा विशस्तथा / परिचारयज्ञाः शूद्रास्तु जपयज्ञा द्विजोत्तमाः
āraṃbhayajñāḥ kṣatrāśca haviryajñā viśastathā / paricārayajñāḥ śūdrāstu japayajñā dvijottamāḥ
The kṣatriyas perform the yajñas of undertaking, and the vaiśyas the yajñas of oblations. The śūdras are devoted to the yajña of service, while the foremost twice-born perform the yajña of sacred japa.