Cupid, thinking he had conquered the sage, then shot his arrow. But all these attempts to seduce Mārkaṇḍeya proved futile, just like the useless endeavors of an atheist.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
विससर्ज तदा बाणं मत्वा तं स्वजितं स्मरः । सर्वं तत्राभवन्मोघमनीशस्य यथोद्यमः
visasarja tadā bāṇaṃ matvā taṃ svajitaṃ smaraḥ | sarvaṃ tatrābhavanmoghamanīśasya yathodyamaḥ
SB 12.8.28