Karshnajinismriti 1.9: Smṛticandrikā · Madanapārijāta · Nirṇayasindhu +2

1.9

bhūtaviddhām amāvāsyāṃ mohād ajñānato 'pi vā | śrāddhakarmaṇi ye kuryus teṣām āyuḥ prahīyate

Those who, through delusion or even through ignorance, perform [rites] on a new-moon day / pierced by the fourteenth lunar day in a śrāddha ritual, their life diminishes.

Those who, through delusion or ignorance, take a new moon joined to the fourteenth for a śrāddha lose their life-span.