Ramayana
वज्राननं वज्रवेगं मेरुमन्दरसन्निभम् । नतं पर्वसु सर्वेषु संयुगेष्वपराजितम् ॥ 7-69-18 ॥
Its face was like the thunderbolt and its speed like the thunderbolt; it resembled Mount Meru and Mandara, was bent at all its joints, and was unconquered in every battle.
english translation