When Lord Nṛsiṁhadeva saw the small boy Prahlāda Mahārāja prostrated at the soles of His lotus feet, He became most ecstatic in affection toward His devotee. Raising Prahlāda, the Lord placed His lotus hand upon the boy’s head because His hand is always ready to create fearlessness in all of His devotees.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
स्वपादमूले पतितं तमर्भकं विलोक्य देवः कृपया परिप्लुतः । उत्थाप्य तच्छीर्ष्ण्यदधात्कराम्बुजं कालाहिवित्रस्तधियां कृताभयम्
svapādamūle patitaṃ tamarbhakaṃ vilokya devaḥ kṛpayā pariplutaḥ | utthāpya tacchīrṣṇyadadhātkarāmbujaṃ kālāhivitrastadhiyāṃ kṛtābhayam
SB 7.9.5