Shiva Purana

siva.sh/siva-purana/saturda-samhita/36/18

कृष्णोपदेशतश्शम्भोस्तपः कृत्वातिदारुणम् ।। प्राप्य चास्त्रं शम्भुवराज्जिग्ये तानर्जुनस्ततः ।। १८।।

sanskrit

At the instance of Kṛṣṇa, Arjuna, performed the severe penance of Śiva and obtained a divne missile duo to Śiva’s boon. He then conquered the Kauravas.

english translation

kRSNopadezatazzambhostapaH kRtvAtidAruNam || prApya cAstraM zambhuvarAjjigye tAnarjunastataH || 18||

hk transliteration by Sanscript