Manusmriti
एषोऽनुपस्कृतः प्रोक्तो योधधर्मः सनातनः । अस्माद् धर्मान्न च्यवेत क्षत्रियो घ्नन् रणे रिपून् ॥ ९८ ॥
Thus has been declared the blameless, primeval law for warriors; from this law a Kshatriya must not depart, when he strikes his foes in battle.
english translation
eSo'nupaskRtaH prokto yodhadharmaH sanAtanaH । asmAd dharmAnna cyaveta kSatriyo ghnan raNe ripUn ॥ 98 ॥
hk transliteration by Sanscript