There is optionally the substitution of ā in the room of the diphthong of the verb khid 'to suffer pain', in the chandas,
The word विभाषा is understood here. Thus चित्तं चिखाद or चिखेद ॥ In secular literature we have चित्तं खेदयति ॥,
खिदेश् छन्दसि
Adhyāya 6 · Pāda 1 · Rule 52