A kind of Lokopacāra Vinaya (formal rules of modesty);
to show modesty to someone as a reciprocal action.
'kṛtapratikṛtitā' kṛte bhaktādinopacāre prasannā guravah pratikṛtiṃ- pratyupakaraṇaṃ sūtrādidanataḥ kariṣyantīti bhaktādidānaṃ prati yatitavyam.
(Sthā 7.137 Vṛ Pa 388)