sadā smaya ityādau sakārādeḥ paro 'kārādiḥ sakāravivakṣāsambhūtavivakṣāntaratas tataḥ utpadyate
In words like "sadā" and "smaya", after the initial [letter] 's', there is the vowel 'a', [which] arises from another desire [to speak] born from the desire to pronounce 's'