6.1.132 etattadoHa sulopo'koranaJsamAse hali
...............
In the case of an 'etad' or 'tad' declension that has the 'su' pratyaya, if the following letter is an 'hal', elide the 'su'.
RULE: etadtadoHa-(GEN-D) sulopaHa-(NOM-S) akoHa-(GEN-D) anaJsamAse-(LOC-S) hali-(LOC-S)
[ elision ('lopa') of the 'su' Nominative Singular Case affix of the Pronominal 'etad' or 'tad' occurs if the Pronominal is succeeded by 'hal', and is not in a negated 'samAsa' compound word, and the Pronominal does not have the 'akach' affix {5.3.71}]
The following illustration derives the form shown in the examples below:
BG 1.13sa shabdastumulo ⇐{6.1.132}
sas shabdastumulo
BG 1.13
Underlying: tatas shaNkhAs cha bheryas cha paNNavAnakagomukhAs , sahasA eva abhyahanyanta sas shabdas tumulas abhavat .sa shabdaHa
BG 1.19
Underlying: sas ghoSHas dhArtarASHTrANNAm hRudayAni vyadArayat , nabhas cha pRuthivIm cha eva tumulas vyanunAdayan .sa ghoSHo
BG 1.27+28
Underlying: tAn samIkSHya sas kOnteyas sarvAn bandhUn avasthitAn kRupayA parayA AviSHTas viSHIdan idam abravIt .sa kOnteyaHa
BG 2.21
Underlying: veda avinAshinam nityam yas enam ajam avyayam , katham sas puruSHas pArtha kam ghAtayati hanti kam .sa puruSHaHa
BG 2.70
Underlying: ApUryamANNam achalapratiSHTham samudram Apas pravishanti yadvat , tadvat kAmAs yam pravishanti sarve sas shAntim Apnoti na kAmakAmI .sa shAntimApnoti
BG 2.71
Underlying: vihAya kAmAn yas sarvAn pumAn charati niHaspRuhas , nirmamas nirahaNkAras sas shAntim adhigachchhati .sa shAntimadhigachchhati