Manava Dharmashastra 3.266

3.266

daśamyādīnāṃ vacanātphalātiśayotpattiḥ | anyāsvapi tu satyāṃ śraddhāyāṃ kartavyam | caturdaśyāṃ tu niṣedha eva |

Medhātithi’s commentary (manubhāṣya):
The mention of the days beginning with the tenth, indicates that the offering is attended by excellent results. So that on other days also the offering is to be made, if due faith is there. But on the fourteenth day there is absolute prohibition.—(276)