Shiva Purana
मंत्राः सर्वैः पदैर्व्याप्ता वाक्यभावात्पदानि च ॥ वर्णैर्वर्णसमूहं हि पदमाहुर्विपश्चितः ॥ १३ ॥
The mantras are pervaded by the words constituting the statement. The words are pervaded by letters. Learned men call the group of letters a word.
english translation
maMtrAH sarvaiH padairvyAptA vAkyabhAvAtpadAni ca ॥ varNairvarNasamUhaM hi padamAhurvipazcitaH ॥ 13 ॥
hk transliteration by Sanscript