In the room of ha after (a sonant Mute) there is optionally a letter homogenous with the prior.,
The pratyahara झय् includes all Mutes. But practically sonant Mutes are only taken here.
As वाक् + हसति = वाग्घसति or वाग् हसति, श्वलिड् ढसति or हसति, अग्निचिद् धसति or हसति, त्रिष्टुब् भसति or हसति, सोमसुद् धसति or सोमसुद् हसति ॥
Why do we say झयः 'after a sonant Mute?' Observe प्राङ् हसति, भवान् हसति ॥,