Yājñavalkya Śikṣā 146

146

pādādau ca padādau ca sam̐yyogāvagraheṣu ca
līḍhā'tilīḍhā vidyucca śaṣaseṣu prakīrtitāḥ

At the beginning of a quarter-verse, at the beginning of a word, and in consonant clusters and word-division pauses, / [the spirants] among ś, ṣ, and s are proclaimed as līḍhā, atilīḍhā, and vidyut.