It was by Droṇācārya’s mercy that you learned the military art of throwing arrows and the confidential art of controlling weapons.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
सरहस्यो धनुर्वेदः सविसर्गोपसंयमः । अस्त्रग्रामश्च भवता शिक्षितो यदनुग्रहात्
sarahasyo dhanurvedaḥ savisargopasaṃyamaḥ | astragrāmaśca bhavatā śikṣito yadanugrahāt
SB 1.7.44