Aśauca-vidhi (Rules of Impurity) within Śrāddha-kalpa — Chapter on Testing/Selecting Brahmanas and Honoring the Atithi
वानप्रस्थो गृहस्थश्च सतामभ्यागतो यथा / वालखिल्यो यतिश्चैव विज्ञेयो ह्यतिथिः सदा
vānaprastho gṛhasthaśca satāmabhyāgato yathā / vālakhilyo yatiścaiva vijñeyo hyatithiḥ sadā
A vānaprastha or a householder who comes to the dwelling of the virtuous, and likewise a vālakhilya and a yati—each should always be known as an atithi.