Reference for Arakhin 9:34

לא אשכחן בערכין דאין נידון בהשג יד או דלמא

<big><b>GEMARA: </b></big>Our Rabbis taught: If one evaluates a person less than one month old, R'Meir says, He gives his worth [its market value], but the Sages say, 'He has said nothing'.

Jastrow