Shiva Purana

siva.sh/siva-purana/kotirudra-samhita/21/11

स्वानुरूपां प्रतिज्ञां स सत्यं चैव करिष्यति ।। सत्यप्रतिज्ञो भगवाञ्छिवश्चेति श्रुतौ श्रुतः ।। ११ ।।

sanskrit

Lord Śiva is reputed in the Vedas as true to his promise. He carries out his promises in the interest of his devotees.

english translation

svAnurUpAM pratijJAM sa satyaM caiva kariSyati || satyapratijJo bhagavAJchivazceti zrutau zrutaH || 11 ||

hk transliteration by Sanscript