8.4.63 shashchho'Ti
...............
This is one of the consonant sandhi sutras.
When a 'sh' is preceded by a 'jhay' and it is also succeeded by an 'aT', optionally replace it with 'chh'.
The following illustration shows the derivation of an example shown below:
BG 2.7
yachchhreyaHa ⇐{8.4.63}
yach shreyaHa ⇐{8.4.55}
yaj shreyaHa ⇐{8.4.40}
yad shreyaHa ⇐{8.2.39}
yat shreyaHa
BG 2.7
Underlying: kArpaNNyadoSHopahatasvabhAvas pRuchchhAmi tvAm dharmasaNmUDhachetAs , yat shreyas syAt nishchitam brUhi tat me shiSHyas te aham shAdhi mAm tvAm prapannam .yachchhreyaHa
BG 2.8
Underlying: na hi prapashyAmi mama apanudyAt yat shokam uchchhoSHaNNam indriyANNAm , avApya bhUmO asapatnam Ruddham , rAjyam surANNAm api cha Adhipatyam .yachchhokamuchchhoSHaNNamindriyANNAm
BG 2.31
Underlying: svadharmam api cha avekSHya na vikampitum arhasi , dharmyAt hi yuddhAt shreyas anyat kSHatriyasya na vidyate .yuddhAchchhreyo