Natyashastra
चतुष्पदा भवेत्सा तु चतुरश्रा तथैव च । चतुर्भिस्सन्निपातैश्च त्रिलया त्रियतिस्तथा ॥ ६०॥
"She (the chant) should be four-footed, with four syllables in the same manner, and with four conjunctions, it becomes a triple rhythm with three measures."
english translation
catuSpadA bhavetsA tu caturazrA tathaiva ca । caturbhissannipAtaizca trilayA triyatistathA ॥ 60॥
hk transliteration by Sanscript