Srimad-Bhagavatam: Canto 9 - Chapter 1 - Verse 17
Sanskrit:
गत्वा माहिष्मतीं रामो ब्रह्मघ्नविहतश्रियम् ।तेषां स शीर्षभी राजन् मध्ये चक्रे महागिरिम् ॥ १७ ॥
ITRANS:
gatvā māhiṣmatīṁ rāmobrahma-ghna-vihata-śriyamteṣāṁ sa śīrṣabhī rājanmadhye cakre mahā-girim
Translation:
O King, Lord Paraśurāma then went to Māhiṣmatī, which was already doomed by the sinful killing of a brāhmaṇa. In the midst of that city he made a mountain of heads, severed from the bodies of the sons of Kārtavīryārjuna.