Markandeya Purana 7.38

7.38

viśvāmitra uvāca
tathāpi khalu dātavyā tvayā me yajñadakṣiṇā /
viśeṣato brāhmaṇānaṃ hantyadattaṃ pratiśrutam //

Viśvāmitra spoke:
“Nevertheless thou must assuredly give me the sacrificial fee; a promise unfulfilled, especially to brahmans, proves injurious. As long as brahmans delight, O king! in the Rājasūya sacrifice, so long indeed must the fee for the Rājasūya sacrifice he given. After making a promise, one must bestow the gift; and one must fight against assailants; so too the afflicted must he protected; thus hast thou already agreed.”