One type of mutual etiquette amongst the Sāṃbhojika (commonsel co-religionist) ascetics, to invite them for accepting paraphernalia, food etc. or for Svādhyāya (scriptural studies and teaching) and the like.
'nikāe ya' tti nikācanaṃ chandanaṃ nimantraṇamityanarthāntaraṃ, tatra śayyopadhyāhārauḥ śiṣyagaṇapradānena svādhyāyena ca sambhyogikah sambhogikaṃ nimantrayan śuddhaḥ...
(Sama 12.2 Vṛ Pa 22)