Agnipurana 331.3

331.3

pādasyādyantu vakraṃ syāt śanau na prathmāsmṛtau /
vālyamuś caturthādvarṇāt pathyā varṇaṃ yujoyataḥ //

The beginning of the quarter is Vakra; śa and nau are not taught as the first; / from the fourth syllable is the Vālyam; Pathyā joins syllables from that [pattern];