Shiva Purana
रोदनाद्द्रावणाच्चैव ते रुद्रा नामतः स्मृताः ॥ ये रुद्रास्ते खलु प्राणा ये प्राणास्ते महात्मकाः ॥ ३० ॥
In view of their crying and flight they are called Rudras. Rudras are vital breaths and vital breaths are Rudras.
english translation
rodanAddrAvaNAccaiva te rudrA nAmataH smRtAH ॥ ye rudrAste khalu prANA ye prANAste mahAtmakAH ॥ 30 ॥
hk transliteration by Sanscript