Ramayana
मत्करोत्सृष्टवज्रेण हनुरस्य यथा हतः । नाम्ना वै कपिशार्दूलो भविता हनुमानिति ॥ 7-36-11 ॥
Since his jaw (hanu) was struck by the thunderbolt hurled from my hand, this tiger among monkeys shall by name become known as Hanuman.
english translation