Comparative evidence

ḱep

• OInd. śap- 'curse' (Whitney 1885: 170); 'swear an oath', 'utter an execration'; 'revile', 'scold', 'blame'; 'curse one's self' (followed by yadi, 'if', i.e. to promise with an oath, vow or swear, "that one will not"); 'adjure', 'supplicate', 'conjure' (anyone) (MW: 1052)

References

MW = Monier-Williams, M. 1899. A Sanskrit-English Dictionary. Clarendon Press.
Whitney 1885 = Whitney W. D. 1885. The roots, verb forms and primary derivatives of the Sanskrit language. A supplement to his Sanskrit grammar. Leipzig.