Shivapurana 3.19.55

Śivapurāṇa (complete text) 3.19.55

niyamaṃ sudṛḍhaṃ dṛṣṭvā suprasanno'bhavanmuniḥ |
durvāsāḥ saprasannātmā varaṃ tasmai pradattavān ||