O my Lord, all the demigods, headed by Lord Brahmā, are sincere servants of Your Lordship, who are situated in a transcendental position. Therefore they are not like us [Prahlāda and his father, the demon Hiraṇyakaśipu]. Your appearance in this fearsome form is Your pastime for Your own pleasure. Such an incarnation is always meant for the protection and improvement of the universe.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
सर्वे ह्यमी विधिकरास्तव सत्त्वधाम्नो ब्रह्मादयो वयमिवेश न चोद्विजन्तः । क्षेमाय भूतय उतात्मसुखाय चास्य विक्रीडितं भगवतो रुचिरावतारैः
sarve hyamī vidhikarāstava sattvadhāmno brahmādayo vayamiveśa na codvijantaḥ | kṣemāya bhūtaya utātmasukhāya cāsya vikrīḍitaṃ bhagavato rucirāvatāraiḥ
SB 7.9.13