Vaishnava Dharmashastra 28.19

28.19

āsīnasya sthitaḥ kuryād abhigacchaṃs tu gacchataḥ | āgacchataḥ pratyudgamya paścād dhāvaṃs tu dhāvataḥ ||

And let him speak, if his teacher sits, standing up; if he walks, advancing towards him; if he is coming near, meeting him; if he runs, running after him;