僧羯磨 1.106

1.106

安受戒人處所法（應安眼見耳不聞處。其受戒人若在空、若隱沒、若離見聞處、若界外，不名受具。和上及足數比丘亦如是。）

The procedure for placing the person receiving the precepts (He should be placed within sight of the eye but beyond the hearing of the ear. If the candidate receiving the precepts is in the air, hidden, beyond sight and hearing, or outside the sīmā, it does not count as receiving upasampadā. The same applies to the upādhyāya and the bhikṣus who complete the quorum.)