Shatapatha Brahmana 1.6.1.18

1.6.1.18

yadyantato yajñasyānuvyāharet | tam prati brūyādapratiṣṭhito daridraḥ kṣipre 'muṃ lokameṣyasīti tathā haiva syāttasmāduha nānuvyāhārīva syāduta hyevaṃvitparo bhavati

If any one were to imprecate evil on him after the completion of the (chief) sacrifice, let him be thus spoken to, 'Unstable and poor, thou shalt swiftly go to yonder world!' for thus it would indeed fare with him. One should not therefore utter imprecations: for whosoever thus understands this has the advantage.