SB 9.15.14

yam āhur vāsudevāṁśaṁ
 haihayānāṁ kulāntakam
triḥ-sapta-kṛtvo ya imāṁ
 cakre niḥkṣatriyāṁ mahīm
Word for word: 
yam — whom (Paraśurāma); āhuḥ — all the learned scholars say; vāsudeva-aṁśam — an incarnation of Vāsudeva, the Supreme Personality of Godhead; haihayānām — of the Haihayas; kula-antakam — the annihilator of the dynasty; triḥ-sapta-kṛtvaḥ — twenty-one times; yaḥ — who (Paraśurāma); imām — this; cakre — made; niḥkṣatriyām — devoid of kṣatriyas; mahīm — the earth.
Translation: 
Learned scholars accept this Paraśurāma as the celebrated incarnation of Vāsudeva who annihilated the dynasty of Kārtavīrya. Paraśurāma killed all the kṣatriyas on earth twenty-one times.