Skandapurana 5.138.15

5.138.15

purā māṃḍavyaśāpena śūdrayonyavatāritaḥ ..
sāṃprataṃ putrarahitaḥ kṛto'pūjyaśca sattama .. 15 ..

“Formerly, by the curse of Māṇḍavya, I was made to descend into the womb of a Śūdra; / now I have been rendered devoid of sons and unworthy of worship, O best of beings!”