The Law Code of Yājñavalkya 3.2.7

3.2.7

śūdrasyotkṛṣṭaṃ brāhmaṃ karma na vidyate | tathā brāhmaṇasyāpakṛṣṭaṃ śaudraṃ karma | madhyame kṣatravaiśyakarmaṇī punar āpadgatasarvavarṇasādhāraṇe iti | śūdraś cāpadgato vaiśyavṛttyā śilpair vā jīvet,

For a Shudra, superior work—the work of a Brahmin—does not exist; likewise for a Brahmin, inferior work—the work of a Shudra [does not exist]. The two intermediate types of work, however—the work of a Kshatriya and of a Vaishya—are common to all classes fallen into distress. And a Shudra who has fallen into distress may live by the livelihood of a Vaishya or by crafts,