Mahabharata 13.131.20

तेन शूद्रान्नशेषेण ब्रह्मस्थानादपाकृतःब्राह्मणः शूद्रतामेति नास्ति तत्र विचारणा

tena śūdrānnaśeṣeṇa brahmasthānādapākṛtaḥbrāhmaṇaḥ śūdratāmeti nāsti tatra vicāraṇā

Our plain-language meaning of this verse is waiting for scholar review.