Manava Dharmashastra 3.127

3.127

prathitā pretakṛtyaiṣā pitryaṃ nāma vidhukṣaye
tasmin yuktasyaiti nityaṃ pretakṛtyaiva laukikī //

Famed is this rite for the dead, called (the sacrifice sacred to the manes (and performed) on the new-moon day; if a man is diligent in (performing) that, (the reward of) the rite for the dead, which is performed according to Smarta rules, reaches him constantly.